Remove instance/ from tracking, fix ruff lint errors

Security:
- Remove instance/.secret_key and instance/stegasoo.db from git
- Add instance/ to .gitignore (was only ignoring frontends/web/instance/)

Lint fixes:
- Remove unused imports in temp_storage.py (os, shutil)
- Sort imports and fix f-string placeholders in cli.py

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.gitignore

@@ -69,6 +69,7 @@ scripts/*
 !scripts/validate-release.sh
 
 # Web UI auth database and SSL certs
+instance/
 frontends/web/instance/
 frontends/web/certs/
 
@@ -87,9 +88,8 @@ frontends/web/temp_files/
 rpi/config.json
 
 # Pre-built Pi tarballs and images (release assets, too large for git)
-rpi/stegasoo-pi-arm64.tar.zst
+rpi/*.tar.zst
-rpi/stegasoo-pi-arm64.tar.zst.zip
+rpi/*.tar.zst.zip
-rpi/stegasoo-venv-pi-arm64.tar.zst
 rpi/*.img
 rpi/*.img.zst
 rpi/*.img.zst.zip

CHANGELOG.md

@@ -5,6 +5,27 @@ All notable changes to Stegasoo will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org).
 
+## [4.1.5] - 2026-01-07
+
+### Added
+- **Developer Documentation**: Educational comments throughout core modules
+  - DCT module: zig-zag diagrams, QIM explanation, Reed-Solomon deep dive
+  - LSB module: visual bit embedding examples, ChaCha20 pixel selection
+  - Crypto module: multi-factor KDF flow diagrams, Argon2id reasoning
+  - CLI module: Click patterns (groups, JSON output, secure input)
+  - Web UI module: Flask architecture, subprocess isolation, async jobs
+- **Pi Test Automation**: `rpi/kickoff-pi-test.sh` script
+  - One command to flash, wait for boot, setup, and smoke test
+  - Self-contained (no dotfile dependencies)
+- **v4.2 Wishlist**: `WISHLIST-4.2.md` for blue-sky ideas (GPU acceleration)
+
+### Changed
+- **Pi MOTD Improvements**:
+  - Dynamic temperature emoji (ice/cool/fire based on temp)
+  - Rocket emoji for service status, globe emoji for URL
+  - Shortened Debian boilerplate message
+  - Fixed escaped variable syntax in heredoc
+
 ## [4.1.3] - 2026-01-05
 
 ### Added
@@ -180,6 +201,7 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 - CLI interface
 - Basic PIN authentication
 
+[4.1.5]: https://github.com/adlee-was-taken/stegasoo/compare/v4.1.3...v4.1.5
 [4.1.3]: https://github.com/adlee-was-taken/stegasoo/compare/v4.1.0...v4.1.3
 [4.1.0]: https://github.com/adlee-was-taken/stegasoo/compare/v4.0.2...v4.1.0
 [4.0.2]: https://github.com/adlee-was-taken/stegasoo/compare/v4.0.1...v4.0.2

PLAN-4.1.0.md

@@ -1,538 +0,0 @@
-# Stegasoo 4.1.0 Plan
-
-## Overview
-
-Version 4.1.0 is a feature release focusing on small-group deployment improvements and new utilities.
-
-## Goals
-
-1. ~~**Multi-User Support** - Admin can create up to 16 users for shared deployments~~ ✅ DONE
-2. **Channel Key QR** - Easy visual sharing of channel keys via QR codes
-3. ~~**CLI Channel Commands** - Manage channel keys from command line~~ ✅ DONE
-4. **Advanced Tools** - Image/stego utilities (TBD)
-
----
-
-## Feature 1: Multi-User Support ✅ COMPLETED
-
-> Implemented in commit 7b33501. All requirements met.
-
-### Requirements
-
-- 16 users + 1 admin maximum (17 total)
-- First user created at setup is always admin
-- Admin can add/delete users, reset passwords
-- Regular users can only change their own password
-- No self-registration (admin-invite only)
-
-### Database Changes
-
-**Update User model in `frontends/web/models.py`:**
-
-```python
-class User(db.Model):
-    id = Column(Integer, primary_key=True)
-    username = Column(String(80), unique=True, nullable=False)
-    password_hash = Column(String(255), nullable=False)
-    role = Column(String(20), default='user')  # 'admin' or 'user'
-    created_at = Column(DateTime, default=datetime.utcnow)
-```
-
-**Migration:** Add `role` and `created_at` columns. Existing users get `role='admin'`.
-
-### New Routes
-
-| Route | Method | Access | Description |
-|-------|--------|--------|-------------|
-| `/admin/users` | GET | admin | List all users |
-| `/admin/users/new` | GET, POST | admin | Create user form |
-| `/admin/users/<id>/delete` | POST | admin | Delete user |
-| `/admin/users/<id>/reset-password` | POST | admin | Generate temp password |
-
-### New Decorator
-
-```python
-# auth.py
-def admin_required(f):
-    @wraps(f)
-    def decorated(*args, **kwargs):
-        if not current_user.is_authenticated:
-            return redirect(url_for('login'))
-        if current_user.role != 'admin':
-            flash('Admin access required', 'error')
-            return redirect(url_for('index'))
-        return f(*args, **kwargs)
-    return decorated
-```
-
-### UI Changes
-
-**Navigation (for admin users):**
-- Add "Users" link in navbar (visible only to admin)
-
-**Account page (`/account`):**
-- Admin sees link to user management
-- All users see their own password change form
-
-**New template: `templates/admin/users.html`:**
-- Table: Username | Role | Created | Actions
-- Actions: Reset Password, Delete (disabled for self)
-- "Add User" button (disabled if at 16 user limit)
-- Show count: "3 of 16 users"
-
-**New template: `templates/admin/user_new.html`:**
-- Username field (email-style allowed)
-- Password field (auto-populated with random 8-char, admin can override)
-- Submit → confirmation page shows password once with copy button
-
-### Validation
-
-- Username: 3-80 chars, alphanumeric + underscore/hyphen + @/. for email-style
-- Password: 8+ chars (same as current)
-- Can't delete yourself
-- Can't demote the last admin
-- Deleting user immediately invalidates their sessions
-
----
-
-## Feature 2: Channel Key QR
-
-### Web UI
-
-**About page additions:**
-
-If `STEGASOO_CHANNEL_KEY` environment variable is set:
-
-```
-┌─────────────────────────────────────────┐
-│  Channel Key                            │
-│                                         │
-│  ██████████████    Your server uses a   │
-│  ██          ██    private channel key. │
-│  ██  ██████  ██    Share this QR with   │
-│  ██  ██████  ██    others to join.      │
-│  ██          ██                         │
-│  ██████████████    [Copy Key] [Download]│
-│                                         │
-│  Key: abc123...xyz                      │
-└─────────────────────────────────────────┘
-```
-
-- QR generated server-side using `qrcode` library
-- "Copy Key" copies text to clipboard
-- "Download QR" saves as PNG
-
-**Implementation:**
-
-```python
-# about route addition
-@app.route('/about')
-def about():
-    channel_key = os.environ.get('STEGASOO_CHANNEL_KEY', '')
-    channel_qr_b64 = None
-    if channel_key:
-        # Generate QR as base64 PNG
-        qr = qrcode.make(channel_key)
-        buffer = BytesIO()
-        qr.save(buffer, format='PNG')
-        channel_qr_b64 = base64.b64encode(buffer.getvalue()).decode()
-    return render_template('about.html',
-                          channel_key=channel_key,
-                          channel_qr=channel_qr_b64)
-```
-
-### CLI Commands
-
-**New command group: `stegasoo channel`**
-
-```bash
-# Generate a new channel key
-stegasoo channel generate
-# Output:
-# Channel Key: stg_abc123...xyz789
-#
-# ██████████████████
-# ██              ██
-# ██  ██████████  ██
-# ...
-#
-# Set in environment: export STEGASOO_CHANNEL_KEY="stg_abc123..."
-
-# Show current key (from env or argument)
-stegasoo channel show
-# Output:
-# Channel Key: stg_abc123...xyz789
-
-# Display QR in terminal (ASCII)
-stegasoo channel qr
-# Output: ASCII QR code
-
-# Save QR as PNG
-stegasoo channel qr -o channel-key.png
-# Output: Saved to channel-key.png
-
-# Explicit format selection
-stegasoo channel qr --format ascii      # Terminal (default)
-stegasoo channel qr --format png -o -   # PNG to stdout
-```
-
-**Implementation notes:**
-
-- Use `qrcode[pil]` for PNG output
-- Use `qrcode` with `print_ascii()` for terminal
-- Read key from `--key` argument or `STEGASOO_CHANNEL_KEY` env var
-- `generate` uses existing `generate_channel_key()` from `stegasoo.channel`
-
----
-
-## File Changes Summary
-
-### New Files
-
-| File | Description |
-|------|-------------|
-| `frontends/web/templates/admin/users.html` | User management page |
-| `frontends/web/templates/admin/user_new.html` | Add user form |
-
-### Modified Files
-
-| File | Changes |
-|------|---------|
-| `frontends/web/models.py` | Add `role`, `created_at` to User |
-| `frontends/web/auth.py` | Add `@admin_required`, user management routes |
-| `frontends/web/templates/base.html` | Add Users link for admins |
-| `frontends/web/templates/account.html` | Add admin link |
-| `frontends/web/templates/about.html` | Add channel key QR section |
-| `src/stegasoo/cli.py` | Add `channel` command group |
-
----
-
-## Testing Plan
-
-### Multi-User
-
-1. Fresh install → first user is admin
-2. Admin can create users up to limit (16)
-3. Admin can't create 17th user (shows error)
-4. Regular user can log in, encode/decode
-5. Regular user can't access `/admin/users`
-6. Admin can reset user password
-7. Admin can delete user
-8. Admin can't delete self
-9. Existing 4.0.2 databases upgrade correctly (single user becomes admin)
-
-### Channel Key QR
-
-1. About page shows nothing if no channel key
-2. About page shows QR + key if channel key set
-3. Copy button works
-4. Download gives valid PNG
-5. QR scans correctly to key value
-
-### CLI
-
-1. `channel generate` creates valid key + shows QR
-2. `channel show` displays current key
-3. `channel qr` outputs ASCII to terminal
-4. `channel qr -o file.png` saves PNG
-5. Commands work with `--key` override
-6. Commands read from env var
-
----
-
-## Feature 3: Advanced Tools
-
-### Included Tools
-
-| Tool | Web | CLI | Description |
-|------|-----|-----|-------------|
-| **Capacity Calculator** | ✓ | ✓ | Upload image → show DCT/LSB capacity |
-| **Metadata Stripper** | ✓ | ✓ | Remove EXIF/metadata from image |
-| **Stego Detector** | ✓ | ✓ | Analyze image for signs of hidden data |
-| **Image Compare** | ✓ | - | Side-by-side before/after diff |
-| **Header Peek** | ✓ | ✓ | Check for Stegasoo header without decrypting |
-| **Batch Mode** | - | ✓ | Encode/decode multiple files |
-
-### Web UI: `/tools` Page
-
-New page with card-based layout:
-
-```
-┌─────────────────────────────────────────────────────────────┐
-│  🛠️ Advanced Tools                                          │
-├─────────────────────────────────────────────────────────────┤
-│                                                             │
-│  ┌─────────────────┐  ┌─────────────────┐                   │
-│  │ 📏 Capacity     │  │ 🧹 Metadata     │                   │
-│  │   Calculator    │  │   Stripper      │                   │
-│  │                 │  │                 │                   │
-│  │ Check how much  │  │ Remove EXIF     │                   │
-│  │ data fits       │  │ before encoding │                   │
-│  └─────────────────┘  └─────────────────┘                   │
-│                                                             │
-│  ┌─────────────────┐  ┌─────────────────┐                   │
-│  │ 🔍 Stego        │  │ 🔎 Header       │                   │
-│  │   Detector      │  │   Peek          │                   │
-│  │                 │  │                 │                   │
-│  │ Analyze image   │  │ Check for       │                   │
-│  │ for hidden data │  │ Stegasoo data   │                   │
-│  └─────────────────┘  └─────────────────┘                   │
-│                                                             │
-│  ┌─────────────────┐                                        │
-│  │ ⚖️ Image        │                                        │
-│  │   Compare       │                                        │
-│  │                 │                                        │
-│  │ Before/after    │                                        │
-│  │ diff view       │                                        │
-│  └─────────────────┘                                        │
-│                                                             │
-└─────────────────────────────────────────────────────────────┘
-```
-
-Each card opens a modal or expands inline for the tool interface.
-
-### CLI Structure
-
-```bash
-# Capacity calculator
-stegasoo capacity image.jpg
-stegasoo capacity image.jpg --format json
-
-# Metadata stripper
-stegasoo strip image.jpg                    # Output to image_stripped.jpg
-stegasoo strip image.jpg -o clean.jpg       # Custom output
-stegasoo strip image.jpg --in-place         # Overwrite original
-
-# Stego detector
-stegasoo detect image.jpg
-stegasoo detect image.jpg --verbose         # Detailed analysis
-
-# Header peek
-stegasoo peek image.jpg
-# Output: "Stegasoo DCT header detected" or "No Stegasoo header found"
-
-# Batch mode
-stegasoo encode --batch manifest.json       # JSON with files + credentials
-stegasoo decode --batch input_dir/ --out output_dir/
-```
-
-### Tool Details
-
-#### Capacity Calculator
-- Input: Image file
-- Output: Dimensions, megapixels, DCT capacity, LSB capacity
-- Web: Upload zone + results panel
-- CLI: Table or JSON output
-
-#### Metadata Stripper
-- Input: Image file
-- Output: Clean image (EXIF/metadata removed)
-- Show what was removed (camera model, GPS, etc.)
-- Preserve image quality
-
-#### Stego Detector
-- Input: Image file
-- Analysis:
-  - Chi-square analysis (LSB detection)
-  - DCT coefficient histogram analysis
-  - Visual inspection hints
-- Output: Likelihood score + findings
-- Note: Detection is probabilistic, not definitive
-
-#### Image Compare
-- Input: Two images (original + stego)
-- Output:
-  - Side-by-side view
-  - Difference overlay (amplified)
-  - Pixel-level stats (PSNR, SSIM)
-- Web only (visual tool)
-
-#### Header Peek
-- Input: Image file
-- Output: Header found (yes/no), mode (DCT/LSB), embedded size estimate
-- Does NOT decrypt - just checks for valid header structure
-- Useful for "is this a stego image?" without credentials
-
-#### Batch Mode
-- CLI only
-- Manifest file (JSON) or directory-based
-- Progress bar for multiple files
-- Error handling per-file (continue on failure)
-
----
-
-## Migration Notes
-
-### Database Migration
-
-For existing 4.0.2 installations:
-
-```python
-# migrations/add_user_role.py
-def upgrade():
-    # Add columns with defaults
-    op.add_column('user', sa.Column('role', sa.String(20), default='user'))
-    op.add_column('user', sa.Column('created_at', sa.DateTime))
-
-    # Set existing users as admin (they were the first user)
-    op.execute("UPDATE user SET role = 'admin' WHERE role IS NULL")
-    op.execute("UPDATE user SET created_at = datetime('now') WHERE created_at IS NULL")
-```
-
-Or simpler: detect on startup, update schema automatically (current pattern).
-
----
-
-## Out of Scope
-
-- Per-user channel keys
-- User groups/teams
-- API authentication tokens
-- User activity logging
-- Password complexity rules beyond length
-
----
-
-## Estimated Effort
-
-| Component | Complexity |
-|-----------|------------|
-| Database schema change | Low |
-| Admin routes + templates | Medium |
-| Access control decorator | Low |
-| About page QR | Low |
-| CLI channel commands | Medium |
-| Advanced Tools (TBD) | Medium-High |
-| Testing | Medium |
-
----
-
-## Decisions
-
-1. **Temp password flow:** Password field auto-populates with random 8-char password. Admin can override if desired. Show password once on confirmation page.
-
-2. **Session handling:** Yes - deleting a user immediately invalidates their active sessions (ban hammer).
-
-3. **Username rules:** Sane requirements, email-style allowed. Validation: 3-80 chars, alphanumeric, underscore, hyphen, @ and . for email-style.
-
----
-
-## Approval
-
-- [x] Plan reviewed
-- [x] Questions resolved
-- [x] Ready to implement
-
-## Progress
-
-- [x] Multi-User Support (commit 7b33501)
-- [x] Channel Key QR (Web UI) - added QR generator on About page
-- [x] CLI Channel Commands
-- [x] Saved Channel Keys (Web UI) - users can save/manage channel keys
-- [x] Advanced Tools - Image Security Toolkit
-  - [x] CLI: `stegasoo tools capacity/strip/peek/exif`
-  - [x] API: `/api/tools/capacity`, `/api/tools/peek`, `/api/tools/exif/*`
-  - [x] WebUI: Tools page with tabbed interface
-  - [x] EXIF Editor with inline editing, clear all, save/download
-
----
-
-## Architectural Improvements (4.1.0)
-
-### Consolidated Channel Key Resolution
-
-Moved `resolve_channel_key()` from 3 duplicate implementations to single source of truth in `src/stegasoo/channel.py`:
-
-```python
-# Library: src/stegasoo/channel.py
-def resolve_channel_key(value, *, file_path=None, no_channel=False) -> str | None:
-    """Unified channel key resolution - returns None (auto), "" (public), or key."""
-
-def get_channel_response_info(channel_key) -> dict:
-    """Get channel info dict for API/WebUI responses."""
-```
-
-Frontends now use thin wrappers that translate exceptions to their context (Click/HTTP).
-
-### DCT Payload Pre-Check
-
-Added `will_fit_by_mode()` pre-check to WebUI encode to fail fast with helpful error message instead of cryptic exception deep in DCT processing.
-
-### EXIF Tools (Library Layer)
-
-Added to `src/stegasoo/utils.py`:
-- `read_image_exif(image_data)` - Read EXIF metadata as dict
-- `write_image_exif(image_data, updates)` - Update EXIF fields (JPEG only)
-
-Dependencies added: `piexif>=1.1.0`
-
----
-
-## Action Item: Architectural Review ✅ DONE
-
-Reviewed modules for consistency with Library → CLI → API → WebUI pattern:
-
-| Module | Library | CLI | API | WebUI | Status |
-|--------|---------|-----|-----|-------|--------|
-| encode | ✓ | ✓ | ✓ | ✓ | Consistent |
-| decode | ✓ | ✓ | ✓ | ✓ | Consistent |
-| channel | ✓ | ✓ | ✓ | ✓ | Consolidated resolve_channel_key |
-| tools | ✓ | ✓ | ✓ | ✓ | Complete |
-| generate | ✓ | ✓ | - | ✓ | CLI has `stegasoo generate` |
-
-Priority order: Developer/CLI → API integrator → WebUI end-user
-
----
-
-## Admin Recovery System (4.1.0) ✅ DONE
-
-Password reset capability for locked-out admins with multiple backup options.
-
-### Library Layer (`src/stegasoo/recovery.py`)
-
-```python
-# Key generation and validation
-generate_recovery_key() -> str       # XXXX-XXXX-XXXX-... (32 chars)
-hash_recovery_key(key) -> str        # SHA-256 for storage
-verify_recovery_key(key, hash) -> bool
-
-# QR code (obfuscated - scans as gibberish)
-obfuscate_key(key) -> str            # XOR with RECOVERY_OBFUSCATION_KEY
-deobfuscate_key(data) -> str | None
-generate_recovery_qr(key) -> bytes   # PNG with obfuscated data
-extract_key_from_qr(image) -> str | None
-
-# Stego backup (hide key in an image)
-create_stego_backup(key, carrier_image) -> bytes
-extract_stego_backup(stego_image, reference) -> str | None
-```
-
-### Database (`app_settings` table)
-
-- `recovery_key_hash` - SHA-256 of recovery key (or null if disabled)
-
-### Web Routes
-
-| Route | Method | Description |
-|-------|--------|-------------|
-| `/setup/recovery` | GET, POST | Step 2 of initial setup |
-| `/recover` | GET, POST | Password reset page |
-| `/recover/stego` | POST | Extract key from stego backup |
-| `/account/recovery/regenerate` | GET, POST | Generate new key |
-| `/account/recovery/disable` | POST | Remove recovery option |
-| `/account/recovery/stego-backup` | POST | Create stego backup |
-
-### CLI Commands
-
-```bash
-stegasoo admin recover --db path/to/stegasoo.db  # Reset password
-stegasoo admin generate-key [--qr]               # Generate key (reference)
-```
-
-### Security Model
-
-1. Recovery key shown once during setup - only hash stored
-2. QR codes XOR'd with `RECOVERY_OBFUSCATION_KEY` (fixed in constants.py)
-3. Stego backups use fixed internal passphrase/PIN - security is obscurity
-4. Instance-bound: recovery key hash must match in target database
-5. Options: text file, QR image, stego image, or no recovery (most secure)

PLAN-4.1.2.md

@@ -1,250 +0,0 @@
-# Stegasoo 4.1.2 Plan
-
-## Release Theme
-Polish and UX improvements after the 4.1.1 stability release.
-
----
-
-## 1. Real Progress Bar for Encode/Decode
-
-**Status:** Done
-
-**Problem:** Users see elapsed time but no indication of how far along the operation is. Long DCT encodes on Pi can take 2-3 minutes with no feedback.
-
-**Solution:** Polling + progress file approach
-
-### Backend Changes
-
-1. **dct_steganography.py** - Write progress during block loop:
-   ```python
-   if progress_file and block_num % 50 == 0:
-       with open(progress_file, 'w') as f:
-           json.dump({"current": block_num, "total": total_blocks, "phase": "embedding"}, f)
-   ```
-
-2. **app.py** - New endpoints:
-   - `POST /encode` returns `job_id`, starts subprocess
-   - `GET /encode/progress/<job_id>` returns progress JSON
-   - `GET /encode/result/<job_id>` returns final result when done
-
-3. **Subprocess wrapper** - Pass progress file path to encode/decode functions
-
-### Frontend Changes
-
-1. **stegasoo.js** - After form submit:
-   - Show progress bar (Bootstrap progress component)
-   - Poll `/encode/progress/{job_id}` every 500ms
-   - Update bar width and percentage text
-   - Show phase (hashing, embedding, encoding, etc.)
-
-2. **Templates** - Add progress bar markup to encode.html and decode.html
-
-### Files to Modify
-- `src/stegasoo/dct_steganography.py`
-- `frontends/web/app.py`
-- `frontends/web/static/js/stegasoo.js`
-- `frontends/web/templates/encode.html`
-- `frontends/web/templates/decode.html`
-
----
-
-## 2. Granular Decode Error Messages
-
-**Status:** Done
-
-**Problem:** Decode failures show generic "Decryption failed" - users don't know if it's wrong photo, wrong passphrase, wrong PIN, corrupted image, or format mismatch.
-
-**Solution:** Bubble up specific error types from library to UI
-
-### Implementation
-- Added new exceptions: InvalidMagicBytesError, ReedSolomonError, NoDataFoundError, ModeMismatchError
-- DCT decode now raises InvalidMagicBytesError for wrong magic bytes
-- DCT decode now raises ReedSolomonError (renamed from reedsolo's) for corruption
-- app.py catches specific exceptions with user-friendly messages:
-  - Invalid magic → "Try a different mode (LSB/DCT)"
-  - RS error → "Image too corrupted, may have been re-saved"
-  - Invalid header → "Image may have been modified"
-  - Decryption error → "Wrong credentials"
-
-### Files Modified
-- `src/stegasoo/exceptions.py` (new exceptions)
-- `src/stegasoo/__init__.py` (exports)
-- `src/stegasoo/dct_steganography.py` (raise specific exceptions)
-- `frontends/web/app.py` (catch and display)
-
----
-
-## 3. Mobile-Responsive Polish
-
-**Status:** Done
-
-**Problem:** UI works on mobile but has rough edges - cramped buttons, hard-to-tap targets, awkward layouts on small screens.
-
-**Solution:** Targeted CSS/layout fixes for mobile breakpoints
-
-### Areas to Improve
-
-1. **Encode/Decode Forms:**
-   - Stack image drop zones vertically on mobile (currently side-by-side)
-   - Larger touch targets for file inputs
-   - Full-width buttons on small screens
-   - Passphrase input readable at smaller sizes
-
-2. **Navigation:**
-   - Hamburger menu for mobile navbar (if not already)
-   - Sticky header doesn't eat too much screen
-   - Easy thumb reach for main actions
-
-3. **Results/Output:**
-   - Download buttons full-width on mobile
-   - QR codes sized appropriately
-   - Click-to-copy message box works well with touch
-
-4. **Drop Zones:**
-   - Larger tap targets
-   - Visual feedback for touch (not just hover)
-   - Camera integration hint on mobile ("Tap to take photo or choose file")
-
-### Testing Targets
-- iPhone SE (small)
-- iPhone 14 (medium)
-- iPad (tablet)
-- Android Chrome
-
-### Files to Modify
-- `frontends/web/static/css/style.css` (or new mobile.css)
-- `frontends/web/templates/encode.html`
-- `frontends/web/templates/decode.html`
-- `frontends/web/templates/base.html` (navbar)
-
----
-
-## Testing Checklist
-
-- [ ] Progress bar works on localhost
-- [ ] Progress bar works on Pi (slower, more visible)
-- [ ] Cancellation handling (what if user navigates away?)
-- [ ] Error states display correctly
-- [ ] Smoke test passes
-
----
-
-## 4. Forced First-Login Setup
-
-**Status:** Done
-
-**Problem:** Users can navigate the app without creating an admin account first. Should force password setup before anything else.
-
-**Solution:** Middleware/decorator that redirects to setup page if no users exist.
-
-### Implementation
-- Added `@app.before_request` hook that redirects to /setup if no users exist
-- Skips redirect for static files and setup-related routes
-
-### Files Modified
-- `frontends/web/app.py` (added require_setup before_request hook)
-
----
-
-## 5. Dropzone UX Fixes
-
-**Status:** Done
-
-**Problem:** Dropzone has some interaction bugs:
-- Dropzone doesn't clear properly if first QR image fails
-- Can't click on image preview to replace file (have to click surrounding border)
-
-**Solution:** Fix JS event handling and state management
-
-### Implementation
-- Added click handler on preview images to trigger file input
-- Made entire drop zone clickable (not just label)
-- QR zone now resets after 2 seconds on error, allowing retry
-- Clear file input on QR error so same file can be re-selected
-
-### Files Modified
-- `frontends/web/static/js/stegasoo.js`
-
----
-
-## 6. Smoke Test Benchmarking
-
-**Status:** Done
-
-**Problem:** No way to measure encode/decode performance or track regressions.
-
-**Solution:** Add timing to smoke tests using `hyperfine` or `time`.
-
-### Implementation
-- Added `--benchmark` flag to run encode/decode benchmarks after tests
-- Added `--runs=N` flag to customize number of benchmark runs (default: 5)
-- Uses hyperfine if available for precise timing with warmup
-- Falls back to manual timing with bc if hyperfine not installed
-- Outputs min/max/avg stats for both encode and decode operations
-
-### Files Modified
-- `tests/smoke-test.sh`
-
----
-
-## 7. Docker Cleanup
-
-**Status:** Done (4.1.1)
-
-**Problem:** Docker build context is larger than needed (includes test images, rpi scripts, etc.)
-
-**Solution:** Added `.dockerignore` and fixed volume permissions in Dockerfile
-
-### Files Modified
-- `.dockerignore` (created)
-- `Dockerfile` (instance dir permissions)
-
----
-
-## 8. Release Validation Script
-
-**Status:** Done
-
-**Problem:** Manual release checklist is error-prone. Need automated validation.
-
-**Solution:** Script that runs through testable checklist items
-
-### Features
-- Run pytest
-- Build and test Docker image
-- SSH to Pi and run smoke test (optional, if PI_IP provided)
-- Report pass/fail summary
-
-### Files to Create
-- `scripts/validate-release.sh`
-
----
-
-## 9. Smoke Test Docker Support
-
-**Status:** Done
-
-**Problem:** Smoke test expects systemd service, doesn't auto-create admin for Docker.
-
-**Solution:** Make smoke test Docker-aware
-
-### Features
-- Skip systemd checks if not on Pi/Linux with systemd
-- Auto-detect fresh Docker (no users) and create admin via /setup
-- Add `--docker` flag to skip Pi-specific checks
-
-### Implementation
-- Added `--docker` flag that sets localhost and skips SSH/systemd checks
-- Docker health check verifies container responds with HTTP 200/302
-- Header shows "Docker Smoke Test" in Docker mode
-
-### Files Modified
-- `rpi/smoke-test.sh`
-
----
-
-## Notes
-
-- Keep 4.1.2 focused - 9 features (9 done)
-- Don't break DCT compatibility (4.1.1 RS format is stable)
-- Test on Pi before release

PLAN-4.1.3.md

@@ -1,42 +0,0 @@
-# Stegasoo 4.1.3 Plan
-
-## Release Theme
-Performance and admin features.
-
----
-
-## 1. DCT Performance Optimizations
-
-**Status:** Planned
-
-**Problem:** DCT encode/decode can be slow on Pi, especially for large images.
-
-**Ideas:**
-- Vectorize block processing with NumPy
-- Reduce Python loop overhead
-- Parallel block processing (multiprocessing?)
-- Profile and identify bottlenecks
-- Consider Cython for hot paths
-
----
-
-## 2. User Management UI
-
-**Status:** Planned
-
-**Problem:** No way for admin to manage users via UI. Currently need direct DB access.
-
-**Features:**
-- List all users
-- Create new user (admin only)
-- Delete user (admin only)
-- Reset user password
-- User activity/last login
-
----
-
-## Notes
-
-- These are heavier lifts than 4.1.2
-- Profile before optimizing
-- Consider security implications of user management

PLAN-4.1.4.md

@@ -1,165 +0,0 @@
-# Stegasoo 4.1.4 Plan
-
-## Build / Deploy
-- [x] Pre-built Python 3.12 venv tarball for Pi (skip 20+ min compile) - see details below
-- [x] Fixed partition sizing in flash script (16GB rootfs for faster imaging)
-- [x] Rename `flash-pi.sh` → `flash-stock-img.sh` for clarity
-- [x] pip-audit integration in release validation
-
-### Pi venv Tarball Approach
-1. Flash fresh Pi image, let it fully build (20+ min compile)
-2. Once running and working, SSH in and create optimized tarball:
-   ```bash
-   cd /opt/stegasoo
-   # Strip caches and tests (295MB → 208MB)
-   find venv/ -type d -name '__pycache__' -exec rm -rf {} + 2>/dev/null
-   find venv/ -type d -name 'tests' -exec rm -rf {} + 2>/dev/null
-   find venv/ -type d -name 'test' -exec rm -rf {} + 2>/dev/null
-   # Compress with zstd (208MB → 39MB)
-   tar -cf - venv/ | zstd -19 -T0 > /tmp/stegasoo-venv-pi-arm64.tar.zst
-   ```
-3. Pull tarball to host: `scp admin@pi:/tmp/stegasoo-venv-pi-arm64.tar.zst rpi/`
-4. setup.sh auto-detects and extracts tarball if present in rpi/
-5. Re-flash and test fresh build with pre-built venv (should be <2 min vs 20+)
-
-## Features
-- [x] QR channel key sharing (see detailed plan below)
-- [ ] Role-based permissions: admin / mod / user
-- [x] `stegasoo info` fastfetch-style command (version, service status, channel, CPU, temp, etc.)
-- [ ] Better capacity estimates / pre-flight check before encode fails
-
----
-
-## QR Channel Key Sharing - Implementation Plan
-
-### Current State
-- ✅ **CLI**: `stegasoo channel qr` generates ASCII/PNG QR for server channel key
-- ✅ **Web UI (about.html)**: Client-side QR generator exists - input key, generate/show QR, download PNG
-- ✅ **Account page**: Shows saved channel keys with fingerprint, rename, delete
-- ❌ No role restrictions on QR sharing
-- ❌ No QR button for saved keys on account page
-- ❌ No QR scanning to import keys
-
-### Design Decisions
-
-**UI Placement** (avoiding encode/decode page crowding):
-- Keep QR generator in **about.html** (already exists, logical place for tools)
-- Add QR button to **account.html** saved keys (small icon, doesn't crowd)
-- Both should be admin-only
-
-**Role Restriction** (per user request):
-- QR sharing = admin only (hide generator + saved key QR buttons from non-admins)
-- Prerequisite: Need role-based permissions feature first
-- Interim option: Just hide from non-admin users using existing `is_admin` flag
-
-### Implementation Steps
-
-#### Phase 1: Admin-only restriction (quick win)
-1. **about.html**: Wrap QR generator section in `{% if is_admin %}` block
-2. **Account route**: Pass `is_admin` to template (if not already)
-3. **account.html**: Add small QR icon button to saved keys row (admin only)
-   - Opens modal with QR canvas (reuse qrcode.js pattern from about.html)
-   - Download PNG button in modal
-
-#### Phase 2: QR Import (optional enhancement)
-1. Add "Import via QR" button to account.html key-add section
-2. Use device camera or file upload to scan QR
-3. Decode and populate channel_key input field
-4. Requires `pyzbar` on server OR client-side JS library like `jsQR`
-
-### Files to Modify
-
-```
-frontends/web/app.py
-  - about() route: Add missing vars: is_admin, channel_configured,
-    channel_fingerprint, channel_source (BUG: currently not passed!)
-  - account() route: ✅ Already passes is_admin
-
-frontends/web/templates/about.html
-  - Wrap channel key QR section in {% if is_admin %}
-
-frontends/web/templates/account.html
-  - Add QR button to saved keys (admin only)
-  - Add QR modal (copy pattern from about.html)
-  - Include qrcode.min.js CDN script
-```
-
-### Bug Found During Research
-The about.html template uses `channel_configured`, `channel_fingerprint`,
-`channel_source` but the route doesn't pass them - always shows "public mode".
-Fix this while implementing QR admin restriction.
-
-### Exact Code Changes
-
-**app.py - Fix about() route (around line 1564):**
-```python
-@app.route("/about")
-def about():
-    from stegasoo.channel import get_channel_status
-    channel_status = get_channel_status()
-
-    # Check if user is admin (for QR sharing)
-    current_user = get_current_user()
-    is_admin = current_user.is_admin if current_user else False
-
-    return render_template(
-        "about.html",
-        has_argon2=has_argon2(),
-        has_qrcode_read=HAS_QRCODE_READ,
-        # Channel info (bugfix)
-        channel_configured=channel_status["configured"],
-        channel_fingerprint=channel_status.get("fingerprint"),
-        channel_source=channel_status.get("source"),
-        # Admin check for QR sharing
-        is_admin=is_admin,
-    )
-```
-
-### Template Changes Preview
-
-**account.html - Add to saved key row:**
-```html
-{% if is_admin %}
-<button type="button" class="btn btn-outline-info btn-sm"
-        onclick="showKeyQr('{{ key.channel_key }}')" title="Show QR">
-    <i class="bi bi-qr-code"></i>
-</button>
-{% endif %}
-```
-
-**about.html - Wrap existing section:**
-```html
-{% if is_admin %}
-<!-- Channel Key QR Generator -->
-<div class="card bg-dark border-secondary">
-    ...existing QR generator...
-</div>
-{% endif %}
-```
-
-### Testing Checklist (Phase 1 Implemented)
-- [ ] Non-admin users cannot see QR generator in about.html
-- [ ] Non-admin users cannot see QR buttons on account page
-- [ ] Admin users can generate QR for any saved key
-- [ ] QR downloads work correctly
-- [ ] QR scans correctly with phone camera
-
-### Implementation Status
-**Phase 1: COMPLETE** - Admin-only QR sharing implemented:
-- `app.py`: Fixed about() route to pass channel status + is_admin
-- `about.html`: QR generator wrapped in `{% if is_admin %}` with Admin badge
-- `account.html`: QR button added to saved keys (admin only), modal + JS for generation/download
-
----
-
-## Security
-- [ ] Optional encryption for temp file storage (paranoid mode, config toggle)
-
-## Docs
-- [x] Update UNDER_THE_HOOD.md (v4.1 changes, channel keys)
-- [ ] General docs refresh
-
-## Ideas (maybe later)
-- [ ] Stego detection tool
-- [ ] Browser extension
-- [ ] Pi snapshot/backup feature

PLAN-4.1.5.md

@@ -1,106 +0,0 @@
-# Stegasoo 4.1.5 Plan
-
-## Decode Progress Bar (Real Progress)
-
-Mirror the encode async pattern for decode operations.
-
-### Backend Changes
-
-**1. Add async mode to `/decode` route (`app.py`)**
-- Check for `async=true` form param
-- Generate job_id, store job, submit to executor
-- Return `{"job_id": ..., "status": "pending"}` immediately
-
-**2. Add decode status/progress endpoints (`app.py`)**
-```python
-@app.route("/decode/status/<job_id>")
-def decode_status(job_id):
-    # Return {"status": "pending|running|complete|error", "result": {...}}
-
-@app.route("/decode/progress/<job_id>")
-def decode_progress(job_id):
-    # Read from /tmp/stegasoo_progress_{job_id}.json
-    # Return {"percent": 0-100, "phase": "..."}
-```
-
-**3. Add `_run_decode_job()` background worker (`app.py`)**
-- Similar to `_run_encode_job()`
-- Pass `progress_file` param to decode function
-- Store result/error in job dict
-
-**4. Update decode functions to write progress (`lsb_steganography.py`, `dct_steganography.py`)**
-
-Phases for decode:
-- `"starting"` (0%)
-- `"reading"` (10%) - reading stego image
-- `"extracting"` (30%) - extracting hidden data
-- `"decrypting"` (60%) - Argon2 + AES decryption
-- `"verifying"` (80%) - HMAC verification
-- `"finalizing"` (95%) - preparing output
-- `"complete"` (100%)
-
-### Frontend Changes
-
-**5. Update decode form submission (`decode.html`)**
-- Add async form handler like encode
-- Call `Stegasoo.submitDecodeAsync(form, btn)`
-
-**6. Add decode async methods (`stegasoo.js`)**
-```javascript
-submitDecodeAsync(form, btn)     // POST with async=true, show modal
-pollDecodeProgress(jobId)        // Poll /decode/status, /decode/progress
-```
-
-Reuse existing:
-- `showProgressModal('Decoding')`
-- `updateProgress(percent, phase)`
-
-**7. Handle decode result redirect**
-- On complete: redirect to `/decode/result/{file_id}` or display inline
-
-### Files to Modify
-
-```
-frontends/web/app.py
-  - Add async handling to /decode route (~line 1300+)
-  - Add /decode/status/<job_id> endpoint
-  - Add /decode/progress/<job_id> endpoint
-  - Add _run_decode_job() function
-
-frontends/web/static/js/stegasoo.js
-  - Add submitDecodeAsync()
-  - Add pollDecodeProgress()
-
-frontends/web/templates/decode.html
-  - Update form submit to use async mode
-
-src/stegasoo/lsb_steganography.py
-  - Add progress_file param to decode()
-  - Write progress at each phase
-
-src/stegasoo/dct_steganography.py
-  - Add progress_file param to decode()
-  - Write progress at each phase
-```
-
-### Testing Checklist
-
-- [ ] Decode shows progress modal on submit
-- [ ] Progress bar animates through phases
-- [ ] Successful decode redirects to result
-- [ ] Failed decode shows error in modal
-- [ ] Works for both LSB and DCT modes
-- [ ] Works for message and file payloads
-- [ ] Progress file cleaned up after completion
-
----
-
-## Other 4.1.5 Ideas (if time)
-
-- [ ] Role-based permissions: admin / mod / user
-- [ ] Better capacity estimates / pre-flight check
-- [ ] Stego detection tool
-
-## Bugs / Nice to Have
-
-- [ ] **flash-stock-img.sh 16GB resize not working** - partition still full SD size after flash, makes dd pull slow. Investigate resize2fs/parted logic and test fix.

RELEASE-4.1.1.md

@@ -1,93 +0,0 @@
-# Stegasoo 4.1.1 Release Notes
-
-**Release Date:** January 5, 2026
-
-## Highlights
-
-- **Reed-Solomon Error Correction** - DCT steganography now includes RS error correction, making encoded images more resilient to minor corruption and compression artifacts
-- **Completely Rewritten Pi Setup** - Fresh install tested and validated, works reliably from scratch
-- **SSH Login Banner** - See your Stegasoo URL immediately on SSH login
-
-## New Features
-
-### Reed-Solomon Error Correction
-DCT-encoded images now include Reed-Solomon error correction codes, allowing recovery from minor image corruption. This significantly improves reliability when images are shared through platforms that may slightly modify them.
-
-### SSH Login Banner (MOTD)
-When you SSH into your Stegasoo Pi, you'll now see:
-```
-  ___  _____  ___    ___    _    ___    ___    ___
- / __||_   _|| __|  / __|  /_\  / __|  / _ \  / _ \
- \__ \  | |  | _|  | (_ | / _ \ \__ \ | (_) || (_) |
- |___/  |_|  |___|  \___//_/ \_\|___/  \___/  \___/
-
- ● Stegasoo is running
-   https://192.168.0.4
-```
-
-### Elapsed Time Counter
-Encode/decode buttons now show elapsed time during operations.
-
-### Click-to-Copy Decoded Message
-Click the decoded message box to copy to clipboard (no button needed).
-
-### Overclock Wizard Option
-First-boot wizard now offers optional CPU overclocking for Pi 4/5 with active cooling.
-
-## Improvements
-
-### Setup Script (setup.sh)
-- Fixed pyenv Python path resolution (handles 3.12 → 3.12.12 mapping)
-- Changed default install location to `/opt/stegasoo`
-- Fixed jpegio build order (clone stegasoo first, then build jpegio into venv)
-- Added python3-dev to dependencies
-- Added btop for system monitoring
-- Shows `/setup` URL at completion for admin account creation
-
-### Sanitize Script
-- Now clears port 443 iptables redirect (clean slate for wizard)
-- Removes overclock settings before imaging
-
-### Documentation
-- Updated all docs to reference `/opt/stegasoo` path
-- Added pre-setup steps (chown /opt, install git)
-- Added Pi 4 performance baseline (~60s for 10MB JPEG)
-
-### About Page
-- Redesigned "Limits & Specs" section with key stats cards and accordion
-
-## Bug Fixes
-
-- Fixed DCT steganography for non-8-aligned images
-- Fixed MOTD port detection (was using iptables which requires root)
-- Fixed smoke test `--443` flag parsing
-
-## Performance
-
-On a Raspberry Pi 4 at 2GHz with USB 3.0 NVMe:
-- ~50 seconds to encode a 10MB JPEG
-- ~60 seconds to decode a 10MB JPEG
-- Full encryption: passphrase + PIN + reference photo
-
-## Upgrade Notes
-
-If upgrading from 4.1.0:
-```bash
-cd /opt/stegasoo  # or ~/stegasoo
-git pull origin 4.1
-```
-
-For fresh installs, see the [Pi README](rpi/README.md).
-
-## Pre-built Images
-
-- `stegasoo-rpi-4.1.1_20260105-2.img.zst` - Raspberry Pi 4/5 image
-
-Flash with:
-```bash
-zstdcat stegasoo-rpi-4.1.1_20260105-2.img.zst | sudo dd of=/dev/sdX bs=4M status=progress
-```
-
----
-
-Full changelog: [v4.1.0...v4.1.1](https://github.com/adlee-was-taken/stegasoo/compare/v4.1.0...v4.1.1)

RELEASE_NOTES.md

@@ -1,14 +1,41 @@
-## Stegasoo v4.1.3
+## Stegasoo v4.1.5
 
-### Fixes
+### Developer Experience
-- **SSL Certificate Generation**: First-boot wizard now properly generates self-signed certs when HTTPS is enabled
+- **Educational Code Comments**: Core modules now include detailed explanations
-- **Download Bug Fixed**: No more "File expired or not found" errors - fixed multi-worker temp file sharing
+  - DCT: zig-zag coefficient diagrams, QIM embedding math, Reed-Solomon "Voyager" reference
-- **Docker Build**: Reduced build context from 2.3GB to ~900KB
+  - LSB: visual bit manipulation examples, ChaCha20 pixel selection
+  - Crypto: multi-factor KDF flow diagrams, Argon2id memory-hardness reasoning
+  - CLI/Web: architectural patterns for future contributors
 
-### Improvements
+### Raspberry Pi Improvements
-- Docker memory limits increased to 2GB (prevents OOM on large DCT operations)
+- **Streamlined Image Creation**: `pull-image.sh` now handles everything
-- Decode button now shows loading spinner during processing
+  - Auto-resizes rootfs to exactly 16GB (consistent images from any SD card)
-- Headless Pi flash script with Trixie/NetworkManager support
+  - Disables Pi OS auto-expand
+  - Compresses with zstd
+  - Optional .zst.zip wrapper for GitHub releases
+- **16GB Minimum**: Pre-built images are now 16GB (was variable)
+- **Host Requirements**: `rpi/host-requirements.txt` documents all dependencies
+- **Test Automation**: `kickoff-pi-test.sh` for one-command flash+test cycles
+
+### MOTD Polish
+- Dynamic temperature emoji (ice/cool/fire based on CPU temp)
+- Rocket emoji for service status
+- Cleaner formatting
+
+### Raspberry Pi Image
+Download `stegasoo-rpi-4.1.5.img.zst.zip` from Releases.
+
+```bash
+# Flash (auto-detects SD card)
+sudo ./rpi/flash-image.sh stegasoo-rpi-4.1.5.img.zst.zip
+
+# Or manual
+zstdcat stegasoo-rpi-4.1.5.img.zst | sudo dd of=/dev/sdX bs=4M status=progress
+```
+
+Default login: `admin` / `stegasoo`
+
+First boot runs the setup wizard for WiFi, HTTPS, and channel key configuration.
 
 ### Docker
 ```bash
@@ -16,19 +43,5 @@ docker-compose up -d web  # Web UI on :5000
 docker-compose up -d api  # REST API on :8000
 ```
 
-### Raspberry Pi Image
-Download `stegasoo-rpi-4.1.3.img.zst`, flash to SD card, and boot. The first-boot wizard will guide you through WiFi, HTTPS, and channel key setup.
-
-```bash
-# Flash with included script
-./rpi/flash-image.sh stegasoo-rpi-4.1.3.img.zst /dev/sdX
-
-# First time: save your WiFi credentials
-./rpi/inject-wifi.sh --setup
-
-# Then inject WiFi after flashing
-sudo ./rpi/inject-wifi.sh /dev/sdX
-```
-
 ### Full Changelog
-See [CHANGELOG.md](CHANGELOG.md) for complete details.
+See [CHANGELOG.md](CHANGELOG.md) for complete version history.

WISHLIST-4.2.md

@@ -0,0 +1,42 @@
+# Stegasoo v4.2 Wishlist
+
+Blue sky ideas for future development. No timeline - just capturing thoughts.
+
+---
+
+## Performance
+
+### GPU-Accelerated DCT Encoding/Decoding
+- **Idea**: Leverage GPU for JPEG DCT coefficient manipulation
+- **Potential Approaches**:
+  - OpenCL/CUDA for parallel DCT operations
+  - Raspberry Pi VideoCore IV/VI GPU compute
+  - WebGPU for browser-based acceleration
+- **Challenges**:
+  - jpegio library is CPU-bound (C extension)
+  - Would need custom DCT implementation
+  - Memory transfer overhead may negate gains for small images
+- **Research**:
+  - libjpeg-turbo uses SIMD but not GPU
+  - nvJPEG (NVIDIA) does GPU-accelerated JPEG
+  - Could potentially use GPU for the embedding math, not JPEG decode
+
+---
+
+## Features
+
+(Add ideas here)
+
+---
+
+## Infrastructure
+
+(Add ideas here)
+
+---
+
+## Notes
+
+- This is a living document - add ideas anytime
+- Not all ideas will be implemented
+- Feasibility research needed before committing to roadmap

frontends/web/app.py

@@ -2,23 +2,76 @@
 """
 Stegasoo Web Frontend (v4.0.0)
 
-Flask-based web UI for steganography operations.
+A production Flask application demonstrating proper web architecture patterns.
-Supports both text messages and file embedding.
+This isn't just a quick demo - it's built to run on a Raspberry Pi 24/7.
+
+ARCHITECTURE OVERVIEW
+=====================
+
+    ┌─────────────────────────────────────────────────────────────────────┐
+    │                         FLASK APPLICATION                            │
+    ├─────────────────────────────────────────────────────────────────────┤
+    │                                                                      │
+    │   Routes (/encode, /decode, /api/*)                                  │
+    │       │                                                              │
+    │       ├── auth.py           # Session management, user accounts      │
+    │       ├── temp_storage.py   # File-based temp storage with expiry    │
+    │       ├── subprocess_stego.py  # Isolated encode/decode workers      │
+    │       └── ssl_utils.py      # Self-signed cert generation            │
+    │                                                                      │
+    │   Templates (Jinja2)                                                 │
+    │       └── base.html → encode.html, decode.html, etc.                │
+    │                                                                      │
+    │   Static assets (CSS, JS)                                           │
+    │       └── Vanilla JS, no framework (keeps it simple)                │
+    │                                                                      │
+    └─────────────────────────────────────────────────────────────────────┘
+
+KEY PATTERNS
+============
+
+1. SUBPROCESS ISOLATION
+   Stegasoo's DCT mode uses scipy/jpegio which can crash on malformed input.
+   We run encode/decode in subprocesses so crashes don't take down the server:
+
+       subprocess_stego = SubprocessStego(timeout=180)
+       result = subprocess_stego.encode(carrier, ref, message, ...)
+
+   If the subprocess crashes, we catch it and return an error gracefully.
+
+2. ASYNC JOBS WITH PROGRESS
+   Encoding large images can take 30+ seconds. We use ThreadPoolExecutor
+   to run jobs in background threads with progress reporting:
+
+       job_id = generate_job_id()
+       _executor.submit(_run_encode_job, job_id, params)
+       # Client polls /api/encode/progress/<job_id> for updates
+
+3. CONTEXT PROCESSORS
+   @app.context_processor injects variables into ALL templates:
+
+       return {"version": __version__, "has_dct": has_dct_support()}
+
+   Now every template can use {{ version }} without passing it explicitly.
+
+4. BEFORE_REQUEST HOOKS
+   @app.before_request runs before every request. We use it for:
+   - First-run setup redirect (no users → /setup)
+   - Session validation
+   - Cleanup of old temp files
+
+5. SECURE SECRET KEY
+   Flask sessions need a secret key. We persist it to a file so sessions
+   survive server restarts (otherwise everyone gets logged out).
 
 CHANGES in v4.0.0:
 - Added channel key support for deployment/group isolation
 - New /api/channel/status endpoint
 - Channel key selector on encode/decode pages
-- Messages encoded with channel key require same key to decode
 
 CHANGES in v3.2.0:
 - Removed date dependency from all operations
-- Renamed day_phrase → passphrase
-- No date selection or tracking needed
 - Simplified user experience for asynchronous communications
-
-NEW in v3.0: LSB and DCT embedding modes with advanced options.
-NEW in v3.0.1: DCT output format selection (PNG or JPEG) and color mode (grayscale or color).
 """
 
 import io
@@ -31,6 +84,7 @@ import time
 from concurrent.futures import ThreadPoolExecutor
 from pathlib import Path
 
+import temp_storage
 from auth import (
     MAX_CHANNEL_KEYS,
     MAX_USERS,
@@ -83,7 +137,6 @@ from flask import (
 )
 from PIL import Image
 from ssl_utils import ensure_certs
-import temp_storage
 
 os.environ["NUMPY_MADVISE_HUGEPAGE"] = "0"
 os.environ["OMP_NUM_THREADS"] = "1"
@@ -157,8 +210,35 @@ except ImportError:
 # ============================================================================
 # SUBPROCESS ISOLATION FOR STEGASOO OPERATIONS
 # ============================================================================
-# Runs encode/decode/compare in subprocesses to prevent jpegio/scipy crashes
+#
-# from taking down the Flask server.
+# This is a critical reliability pattern. Here's the problem:
+#
+# scipy's DCT and jpegio can crash (segfault) on:
+# - Malformed JPEG files
+# - Very large images that exhaust memory
+# - Certain edge cases in coefficient manipulation
+#
+# If these crash in the main Flask process, your whole server dies.
+# Users get a connection reset, and the service goes down.
+#
+# The solution: Run stegasoo operations in separate Python processes.
+#
+#     Main Flask process                 Worker subprocess
+#     ┌─────────────────┐               ┌─────────────────┐
+#     │                 │   spawn       │                 │
+#     │  /api/encode    │──────────────>│  encode()       │
+#     │                 │               │                 │
+#     │  wait for       │<──────────────│  return result  │
+#     │  result         │    or crash   │  (or crash)     │
+#     │                 │               │                 │
+#     │  handle error   │               │  (process dies) │
+#     └─────────────────┘               └─────────────────┘
+#
+# If the subprocess crashes, we catch the error and return a friendly message.
+# The main server keeps running. Users can try again with different input.
+#
+# The subprocess_stego module handles all the pickling/unpickling of data.
+
 from subprocess_stego import (
     SubprocessStego,
     cleanup_progress_file,
@@ -169,6 +249,7 @@ from subprocess_stego import (
 
 from stegasoo.qr_utils import (
     can_fit_in_qr,
+    decompress_data,
     detect_and_crop_qr,
     extract_key_from_qr,
     generate_qr_code,
@@ -181,38 +262,89 @@ subprocess_stego = SubprocessStego(timeout=180)  # 3 minute timeout for large im
 # ============================================================================
 # FLASK APP CONFIGURATION
 # ============================================================================
+#
+# Flask configuration demonstrates several production patterns:
+#
+# 1. SECRET KEY PERSISTENCE
+#    Flask uses secret_key to sign session cookies. If it changes, all users
+#    get logged out. We save it to a file so it survives restarts.
+#
+# 2. CONTENT LENGTH LIMITS
+#    MAX_CONTENT_LENGTH prevents DoS via huge uploads. Flask will reject
+#    requests that exceed this before loading them into memory.
+#
+# 3. ENVIRONMENT-BASED CONFIG
+#    Settings come from environment variables, allowing:
+#    - Different settings per deployment (dev/staging/prod)
+#    - Docker/systemd to inject config without code changes
+#    - 12-factor app compliance
+#
+# 4. INSTANCE FOLDER
+#    Flask's instance_path is for per-deployment data (databases, keys).
+#    It's .gitignored by default - perfect for secrets.
 
 app = Flask(__name__)
 
 # Persist secret key so sessions survive restarts
+# Without this, every restart = everyone gets logged out
 _instance_path = Path(app.instance_path)
 _instance_path.mkdir(parents=True, exist_ok=True)
 _secret_key_file = _instance_path / ".secret_key"
 if _secret_key_file.exists():
     app.secret_key = _secret_key_file.read_text().strip()
 else:
-    app.secret_key = secrets.token_hex(32)
+    # First run: generate a new key and save it
+    app.secret_key = secrets.token_hex(32)  # 256 bits of randomness
     _secret_key_file.write_text(app.secret_key)
-    _secret_key_file.chmod(0o600)
+    _secret_key_file.chmod(0o600)  # Only owner can read
 
+# Reject uploads larger than this (prevents memory exhaustion)
 app.config["MAX_CONTENT_LENGTH"] = MAX_FILE_SIZE
 
 # Auth configuration from environment
+# STEGASOO_AUTH_ENABLED=false disables login (for local/dev use)
 app.config["AUTH_ENABLED"] = os.environ.get("STEGASOO_AUTH_ENABLED", "true").lower() == "true"
 app.config["HTTPS_ENABLED"] = os.environ.get("STEGASOO_HTTPS_ENABLED", "false").lower() == "true"
 
-# Initialize auth module
+# Initialize auth module (sets up session handling, user DB)
 init_auth(app)
 
 # ============================================================================
 # ASYNC JOB MANAGEMENT (v4.1.2)
 # ============================================================================
-# Encode operations can run in background threads with progress reporting
+#
+# Problem: DCT encoding a large image can take 30-60 seconds.
+# Solution: Run it in a background thread, let the client poll for progress.
+#
+# The flow:
+#
+#     Client                          Server
+#     ──────                          ──────
+#     POST /api/encode/async ──────>  Start background job
+#                            <──────  Return job_id
+#
+#     GET /api/encode/progress/123 ─>  Check job status
+#                            <──────  {"progress": 45, "phase": "embedding"}
+#
+#     GET /api/encode/progress/123 ─>  Check again
+#                            <──────  {"status": "complete", "file_id": "abc"}
+#
+#     GET /api/download/abc ────────>  Download result
+#                            <──────  Encoded image
+#
+# Why ThreadPoolExecutor instead of Celery/Redis?
+# - This runs on a Raspberry Pi with 1GB RAM
+# - We don't need distributed workers
+# - Keep it simple - threads are fine for 2 concurrent jobs
+#
+# The thread pool is limited to 2 workers because:
+# - Each encode loads the full image into memory
+# - Too many concurrent jobs = OOM on the Pi
 
-# Thread pool for background encode/decode operations
 _executor = ThreadPoolExecutor(max_workers=2)
 
-# Job storage: job_id -> {status, result, error, file_id, ...}
+# Job storage: job_id -> {status, result, error, file_id, created, ...}
+# We use a dict with a lock because threads access it concurrently
 _jobs = {}
 _jobs_lock = threading.Lock()
 
@@ -267,6 +399,27 @@ THUMBNAIL_FILES: dict[str, bytes] = {}  # Not used - see temp_storage.py
 # ============================================================================
 # TEMPLATE CONTEXT PROCESSOR
 # ============================================================================
+#
+# Context processors inject variables into EVERY template automatically.
+# Instead of passing the same data to every render_template() call:
+#
+#     # Bad: repetitive and error-prone
+#     return render_template("page.html", version=__version__, has_dct=...)
+#
+# We define it once here and it's available everywhere:
+#
+#     # In any template:
+#     <p>Version: {{ version }}</p>
+#     {% if has_dct %}DCT mode available{% endif %}
+#
+# This is great for:
+# - Version numbers (show in footer)
+# - Feature flags (has_dct, auth_enabled)
+# - User info (username, is_admin)
+# - Global config (max sizes, limits)
+#
+# The function runs on EVERY request, so keep it fast.
+# Don't do expensive database queries here.
 
 
 @app.context_processor
@@ -1049,12 +1202,19 @@ def encode_page():
             ref_data = ref_photo.read()
             carrier_data = carrier.read()
 
-            # Handle RSA key - can come from .pem file or QR code image
+            # Handle RSA key - can come from .pem file, QR code image, or webcam-scanned PEM (v4.1.5)
             rsa_key_data = None
+            rsa_key_pem = request.form.get("rsa_key_pem", "").strip()
             rsa_key_qr = request.files.get("rsa_key_qr")
             rsa_key_from_qr = False
 
-            if rsa_key_file and rsa_key_file.filename:
+            if rsa_key_pem:
+                # Webcam-scanned PEM key (v4.1.5) - may be compressed
+                if rsa_key_pem.startswith("STEGASOO-Z:"):
+                    rsa_key_pem = decompress_data(rsa_key_pem)
+                rsa_key_data = rsa_key_pem.encode("utf-8")
+                rsa_key_from_qr = True
+            elif rsa_key_file and rsa_key_file.filename:
                 rsa_key_data = rsa_key_file.read()
             elif rsa_key_qr and rsa_key_qr.filename and HAS_QRCODE_READ:
                 qr_image_data = rsa_key_qr.read()
@@ -1371,6 +1531,82 @@ def encode_cleanup(file_id):
 # ============================================================================
 
 
+def _run_decode_job(job_id: str, decode_params: dict) -> None:
+    """Background thread function for async decode."""
+    progress_file = get_progress_file_path(job_id)
+
+    try:
+        _store_job(job_id, {"status": "running", "created": time.time()})
+
+        # Run decode with progress file
+        decode_result = subprocess_stego.decode(
+            stego_data=decode_params["stego_data"],
+            reference_data=decode_params["ref_data"],
+            passphrase=decode_params["passphrase"],
+            pin=decode_params.get("pin"),
+            rsa_key_data=decode_params.get("rsa_key_data"),
+            rsa_password=decode_params.get("rsa_password"),
+            embed_mode=decode_params.get("embed_mode", "auto"),
+            channel_key=decode_params.get("channel_key"),
+            progress_file=progress_file,
+        )
+
+        if not decode_result.success:
+            _store_job(
+                job_id,
+                {
+                    "status": "error",
+                    "error": decode_result.error or "Decoding failed",
+                    "error_type": decode_result.error_type,
+                    "created": time.time(),
+                },
+            )
+            return
+
+        # Store result based on type
+        if decode_result.is_file:
+            file_id = secrets.token_urlsafe(16)
+            filename = decode_result.filename or "decoded_file"
+            temp_storage.save_temp_file(file_id, decode_result.file_data, {
+                "filename": filename,
+                "mime_type": decode_result.mime_type,
+            })
+            _store_job(
+                job_id,
+                {
+                    "status": "complete",
+                    "file_id": file_id,
+                    "is_file": True,
+                    "filename": filename,
+                    "file_size": len(decode_result.file_data),
+                    "mime_type": decode_result.mime_type,
+                    "created": time.time(),
+                },
+            )
+        else:
+            _store_job(
+                job_id,
+                {
+                    "status": "complete",
+                    "is_file": False,
+                    "message": decode_result.message,
+                    "created": time.time(),
+                },
+            )
+
+    except Exception as e:
+        _store_job(
+            job_id,
+            {
+                "status": "error",
+                "error": str(e),
+                "created": time.time(),
+            },
+        )
+    finally:
+        cleanup_progress_file(job_id)
+
+
 @app.route("/decode", methods=["GET", "POST"])
 @login_required
 def decode_page():
@@ -1414,12 +1650,19 @@ def decode_page():
             ref_data = ref_photo.read()
             stego_data = stego_image.read()
 
-            # Handle RSA key - can come from .pem file or QR code image
+            # Handle RSA key - can come from .pem file, QR code image, or webcam-scanned PEM (v4.1.5)
             rsa_key_data = None
+            rsa_key_pem = request.form.get("rsa_key_pem", "").strip()
             rsa_key_qr = request.files.get("rsa_key_qr")
             rsa_key_from_qr = False
 
-            if rsa_key_file and rsa_key_file.filename:
+            if rsa_key_pem:
+                # Webcam-scanned PEM key (v4.1.5) - may be compressed
+                if rsa_key_pem.startswith("STEGASOO-Z:"):
+                    rsa_key_pem = decompress_data(rsa_key_pem)
+                rsa_key_data = rsa_key_pem.encode("utf-8")
+                rsa_key_from_qr = True
+            elif rsa_key_file and rsa_key_file.filename:
                 rsa_key_data = rsa_key_file.read()
             elif rsa_key_qr and rsa_key_qr.filename and HAS_QRCODE_READ:
                 qr_image_data = rsa_key_qr.read()
@@ -1454,6 +1697,29 @@ def decode_page():
                     flash(result.error_message, "error")
                     return render_template("decode.html", has_qrcode_read=HAS_QRCODE_READ)
 
+            # Check for async mode (v4.1.5)
+            is_async = request.form.get("async") == "true" or request.headers.get("X-Async") == "true"
+
+            # Build decode params
+            decode_params = {
+                "stego_data": stego_data,
+                "ref_data": ref_data,
+                "passphrase": passphrase,
+                "pin": pin if pin else None,
+                "rsa_key_data": rsa_key_data,
+                "rsa_password": key_password,
+                "embed_mode": embed_mode,
+                "channel_key": channel_key,
+            }
+
+            # ASYNC MODE: Start background job and return JSON
+            if is_async:
+                job_id = generate_job_id()
+                _store_job(job_id, {"status": "pending", "created": time.time()})
+                _executor.submit(_run_decode_job, job_id, decode_params)
+                return jsonify({"job_id": job_id, "status": "pending"})
+
+            # SYNC MODE: Run inline (original behavior)
             # v4.0.0: Include channel_key parameter
             # Use subprocess-isolated decode to prevent crashes
             decode_result = subprocess_stego.decode(
@@ -1559,6 +1825,92 @@ def decode_download(file_id):
     )
 
 
+# ============================================================================
+# DECODE PROGRESS ENDPOINTS (v4.1.5)
+# ============================================================================
+
+
+@app.route("/decode/status/<job_id>")
+@login_required
+def decode_status(job_id):
+    """Get the status of an async decode job."""
+    job = _get_job(job_id)
+    if not job:
+        return jsonify({"error": "Job not found"}), 404
+
+    response = {"status": job.get("status", "unknown")}
+
+    if job["status"] == "complete":
+        response["is_file"] = job.get("is_file", False)
+        if job.get("is_file"):
+            response["file_id"] = job.get("file_id")
+            response["filename"] = job.get("filename")
+            response["file_size"] = job.get("file_size")
+            response["mime_type"] = job.get("mime_type")
+        else:
+            response["message"] = job.get("message")
+    elif job["status"] == "error":
+        response["error"] = job.get("error", "Unknown error")
+        response["error_type"] = job.get("error_type")
+
+    return jsonify(response)
+
+
+@app.route("/decode/progress/<job_id>")
+@login_required
+def decode_progress(job_id):
+    """Get the progress of an async decode job."""
+    progress = read_progress(job_id)
+    if progress:
+        return jsonify(progress)
+
+    # No progress file yet - check job status
+    job = _get_job(job_id)
+    if not job:
+        return jsonify({"error": "Job not found"}), 404
+
+    if job["status"] == "complete":
+        return jsonify({"percent": 100, "phase": "complete"})
+    elif job["status"] == "error":
+        return jsonify({"percent": 0, "phase": "error", "error": job.get("error")})
+    elif job["status"] == "pending":
+        return jsonify({"percent": 0, "phase": "starting"})
+
+    # Running but no progress file yet
+    return jsonify({"percent": 5, "phase": "reading"})
+
+
+@app.route("/decode/result/<job_id>")
+@login_required
+def decode_result(job_id):
+    """Get the result page for an async decode job."""
+    job = _get_job(job_id)
+    if not job:
+        flash("Job not found or expired.", "error")
+        return redirect(url_for("decode_page"))
+
+    if job["status"] != "complete":
+        flash("Decode not complete.", "error")
+        return redirect(url_for("decode_page"))
+
+    if job.get("is_file"):
+        return render_template(
+            "decode.html",
+            decoded_file=True,
+            file_id=job.get("file_id"),
+            filename=job.get("filename"),
+            file_size=format_size(job.get("file_size", 0)),
+            mime_type=job.get("mime_type"),
+            has_qrcode_read=HAS_QRCODE_READ,
+        )
+    else:
+        return render_template(
+            "decode.html",
+            decoded_message=job.get("message"),
+            has_qrcode_read=HAS_QRCODE_READ,
+        )
+
+
 @app.route("/about")
 def about():
     from stegasoo.channel import get_channel_status
@@ -2332,7 +2684,8 @@ if __name__ == "__main__":
     # HTTPS configuration
     ssl_context = None
     if app.config.get("HTTPS_ENABLED", False):
-        hostname = os.environ.get("STEGASOO_HOSTNAME", "localhost")
+        import socket
+        hostname = os.environ.get("STEGASOO_HOSTNAME") or socket.gethostname()
         try:
             cert_path, key_path = ensure_certs(base_dir, hostname)
             if cert_path.exists() and key_path.exists():

frontends/web/ssl_utils.py

@@ -7,6 +7,7 @@ Uses cryptography library (already a dependency).
 
 import datetime
 import ipaddress
+import socket
 from pathlib import Path
 
 from cryptography import x509
@@ -15,6 +16,33 @@ from cryptography.hazmat.primitives.asymmetric import rsa
 from cryptography.x509.oid import NameOID
 
 
+def _get_local_ips() -> list[str]:
+    """Get local IP addresses for this machine."""
+    ips = []
+    try:
+        # Get hostname and resolve to IP
+        hostname = socket.gethostname()
+        for addr_info in socket.getaddrinfo(hostname, None, socket.AF_INET):
+            ip = addr_info[4][0]
+            if ip not in ips and not ip.startswith("127."):
+                ips.append(ip)
+    except Exception:
+        pass
+
+    # Also try connecting to external to get primary interface IP
+    try:
+        s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        s.connect(("8.8.8.8", 80))
+        ip = s.getsockname()[0]
+        if ip not in ips:
+            ips.append(ip)
+        s.close()
+    except Exception:
+        pass
+
+    return ips
+
+
 def get_cert_paths(base_dir: Path) -> tuple[Path, Path]:
     """Get paths for cert and key files."""
     cert_dir = base_dir / "certs"
@@ -64,12 +92,26 @@ def generate_self_signed_cert(
         x509.DNSName("localhost"),
         x509.IPAddress(ipaddress.IPv4Address("127.0.0.1")),
     ]
+
+    # Add hostname.local for mDNS access
+    if not hostname.endswith(".local"):
+        san_list.append(x509.DNSName(f"{hostname}.local"))
+
     # Add the hostname as IP if it looks like one
     try:
         san_list.append(x509.IPAddress(ipaddress.IPv4Address(hostname)))
     except ipaddress.AddressValueError:
         pass
 
+    # Add local network IPs
+    for local_ip in _get_local_ips():
+        try:
+            ip_addr = ipaddress.IPv4Address(local_ip)
+            if x509.IPAddress(ip_addr) not in san_list:
+                san_list.append(x509.IPAddress(ip_addr))
+        except (ipaddress.AddressValueError, ValueError):
+            pass
+
     now = datetime.datetime.now(datetime.timezone.utc)
     cert = (
         x509.CertificateBuilder()

frontends/web/static/js/generate.js

@@ -231,20 +231,14 @@ const StegasooGenerate = {
         printWindow.document.write(`<!DOCTYPE html>
 <html>
 <head>
-    <title>Stegasoo RSA Key QR Code</title>
+    <title>QR Code</title>
     <style>
-        body { display: flex; flex-direction: column; align-items: center; justify-content: center; min-height: 100vh; margin: 0; font-family: sans-serif; }
+        body { display: flex; flex-direction: column; align-items: center; justify-content: center; min-height: 100vh; margin: 0; }
         img { max-width: 400px; }
-        .warning { margin-top: 20px; padding: 10px; border: 2px solid #ff9800; background: #fff3e0; max-width: 400px; text-align: center; font-size: 12px; }
     </style>
 </head>
 <body>
-    <h2>Stegasoo RSA Private Key</h2>
+    <img src="${qrImg.src}" alt="QR Code">
-    <img src="${qrImg.src}" alt="RSA Key QR Code">
-    <div class="warning">
-        <strong>Warning:</strong> This QR code contains your unencrypted RSA private key.
-        Store securely and destroy after use.
-    </div>
     <script>window.onload = function() { window.print(); }<\/script>
 </body>
 </html>`);

frontends/web/static/js/stegasoo.js

@@ -1090,6 +1090,400 @@ const Stegasoo = {
         if (phaseText) phaseText.textContent = phase;
     },
 
+    // ========================================================================
+    // ASYNC DECODE WITH PROGRESS (v4.1.5)
+    // ========================================================================
+
+    /**
+     * Submit decode form asynchronously with progress tracking
+     * @param {HTMLFormElement} form - The decode form
+     * @param {HTMLElement} btn - The submit button
+     */
+    async submitDecodeAsync(form, btn) {
+        const formData = new FormData(form);
+        formData.append('async', 'true');
+
+        // Show progress modal
+        this.showProgressModal('Decoding');
+
+        try {
+            // Start decode job
+            const response = await fetch('/decode', {
+                method: 'POST',
+                body: formData,
+            });
+
+            if (!response.ok) {
+                throw new Error('Failed to start decode');
+            }
+
+            const result = await response.json();
+
+            if (result.error) {
+                throw new Error(result.error);
+            }
+
+            const jobId = result.job_id;
+
+            // Poll for progress
+            await this.pollDecodeProgress(jobId);
+
+        } catch (error) {
+            this.hideProgressModal();
+            alert('Decode failed: ' + error.message);
+            btn.disabled = false;
+            btn.innerHTML = '<i class="bi bi-unlock-fill me-2"></i>Decode';
+        }
+    },
+
+    /**
+     * Poll decode progress until complete
+     * @param {string} jobId - The job ID
+     */
+    async pollDecodeProgress(jobId) {
+        const poll = async () => {
+            try {
+                // Check status first
+                const statusResponse = await fetch(`/decode/status/${jobId}`);
+                const statusData = await statusResponse.json();
+
+                if (statusData.status === 'complete') {
+                    // Done - redirect to result page
+                    this.updateProgress(100, 'Complete!');
+                    setTimeout(() => {
+                        window.location.href = `/decode/result/${jobId}`;
+                    }, 500);
+                    return;
+                }
+
+                if (statusData.status === 'error') {
+                    // Handle specific error types
+                    const errorType = statusData.error_type;
+                    let errorMsg = statusData.error || 'Decode failed';
+
+                    if (errorType === 'DecryptionError' || errorMsg.toLowerCase().includes('decrypt')) {
+                        errorMsg = 'Wrong credentials. Double-check your reference photo, passphrase, PIN, and channel key.';
+                    }
+
+                    throw new Error(errorMsg);
+                }
+
+                // Get progress
+                const progressResponse = await fetch(`/decode/progress/${jobId}`);
+                const progressData = await progressResponse.json();
+
+                const percent = progressData.percent || 0;
+                const phase = progressData.phase || 'processing';
+
+                this.updateProgress(percent, this.formatDecodePhase(phase));
+
+                // Continue polling
+                setTimeout(poll, 500);
+
+            } catch (error) {
+                this.hideProgressModal();
+                alert(error.message);
+            }
+        };
+
+        await poll();
+    },
+
+    /**
+     * Format decode phase name for display
+     */
+    formatDecodePhase(phase) {
+        const phases = {
+            'starting': 'Starting...',
+            'reading': 'Reading image...',
+            'extracting': 'Extracting data...',
+            'decrypting': 'Decrypting...',
+            'verifying': 'Verifying...',
+            'finalizing': 'Finalizing...',
+            'complete': 'Complete!',
+        };
+        return phases[phase] || phase;
+    },
+
+    // ========================================================================
+    // WEBCAM QR SCANNING (v4.1.5)
+    // ========================================================================
+
+    /**
+     * Active scanner instance
+     */
+    _qrScanner: null,
+    _qrScannerModal: null,
+    _qrScannerCallback: null,
+
+    /**
+     * Show webcam QR scanner modal
+     * @param {Function} onSuccess - Callback with decoded QR text
+     * @param {string} title - Modal title
+     */
+    showQrScanner(onSuccess, title = 'Scan QR Code') {
+        this._qrScannerCallback = onSuccess;
+
+        // Create modal if doesn't exist
+        let modal = document.getElementById('qrScannerModal');
+        if (!modal) {
+            modal = document.createElement('div');
+            modal.id = 'qrScannerModal';
+            modal.className = 'modal fade';
+            modal.innerHTML = `
+                <div class="modal-dialog modal-dialog-centered">
+                    <div class="modal-content bg-dark text-light">
+                        <div class="modal-header border-secondary">
+                            <h5 class="modal-title">
+                                <i class="bi bi-camera-video me-2"></i>
+                                <span id="qrScannerTitle">${title}</span>
+                            </h5>
+                            <button type="button" class="btn-close btn-close-white" data-bs-dismiss="modal"></button>
+                        </div>
+                        <div class="modal-body p-0">
+                            <div id="qrScannerReader" style="width: 100%;"></div>
+                            <div id="qrScannerStatus" class="text-center py-3 text-muted">
+                                <i class="bi bi-qr-code-scan me-2"></i>
+                                Point camera at QR code
+                            </div>
+                        </div>
+                        <div class="modal-footer border-secondary">
+                            <button type="button" class="btn btn-primary" id="qrCaptureBtn">
+                                <i class="bi bi-camera me-1"></i>Capture
+                            </button>
+                            <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Cancel</button>
+                        </div>
+                    </div>
+                </div>
+            `;
+            document.body.appendChild(modal);
+
+            // Clean up scanner when modal hides
+            modal.addEventListener('hidden.bs.modal', () => {
+                this.stopQrScanner();
+            });
+
+            // Manual capture button
+            modal.querySelector('#qrCaptureBtn')?.addEventListener('click', () => {
+                this.captureQrFrame();
+            });
+        }
+
+        // Update title
+        const titleEl = modal.querySelector('#qrScannerTitle');
+        if (titleEl) titleEl.textContent = title;
+
+        // Reset status
+        const statusEl = modal.querySelector('#qrScannerStatus');
+        if (statusEl) {
+            statusEl.innerHTML = '<i class="bi bi-qr-code-scan me-2"></i>Point camera at QR code';
+            statusEl.className = 'text-center py-3 text-muted';
+        }
+
+        // Show modal
+        this._qrScannerModal = new bootstrap.Modal(modal);
+        this._qrScannerModal.show();
+
+        // Start scanner after modal is shown
+        modal.addEventListener('shown.bs.modal', () => {
+            this.startQrScanner();
+        }, { once: true });
+    },
+
+    /**
+     * Start the QR scanner
+     */
+    startQrScanner() {
+        const readerEl = document.getElementById('qrScannerReader');
+        if (!readerEl) return;
+
+        // Check if Html5Qrcode is available
+        if (typeof Html5Qrcode === 'undefined') {
+            console.error('Html5Qrcode library not loaded');
+            const statusEl = document.getElementById('qrScannerStatus');
+            if (statusEl) {
+                statusEl.innerHTML = '<i class="bi bi-exclamation-triangle text-warning me-2"></i>QR scanner not available';
+            }
+            return;
+        }
+
+        this._qrScanner = new Html5Qrcode('qrScannerReader');
+
+        const config = {
+            fps: 10,
+            qrbox: { width: 250, height: 250 },
+            aspectRatio: 1.0,
+        };
+
+        this._qrScanner.start(
+            { facingMode: 'environment' }, // Prefer back camera
+            config,
+            (decodedText, decodedResult) => {
+                // QR code detected
+                this.onQrCodeDetected(decodedText);
+            },
+            (errorMessage) => {
+                // Scan error (ignore, keep scanning)
+            }
+        ).catch((err) => {
+            console.error('Failed to start scanner:', err);
+            const statusEl = document.getElementById('qrScannerStatus');
+            if (statusEl) {
+                if (err.toString().includes('Permission')) {
+                    statusEl.innerHTML = '<i class="bi bi-camera-video-off text-danger me-2"></i>Camera permission denied';
+                } else {
+                    statusEl.innerHTML = '<i class="bi bi-exclamation-triangle text-warning me-2"></i>Could not access camera';
+                }
+                statusEl.className = 'text-center py-3';
+            }
+        });
+    },
+
+    /**
+     * Capture a frame with countdown and try to decode
+     */
+    captureQrFrame() {
+        const statusEl = document.getElementById('qrScannerStatus');
+        const captureBtn = document.getElementById('qrCaptureBtn');
+        if (!statusEl || !this._qrScanner) return;
+
+        // Disable button during countdown
+        if (captureBtn) captureBtn.disabled = true;
+
+        let count = 3;
+        const countdown = () => {
+            if (count > 0) {
+                statusEl.innerHTML = `<i class="bi bi-camera me-2"></i><span style="font-size: 1.5rem; font-weight: bold;">${count}</span>`;
+                statusEl.className = 'text-center py-3 text-warning';
+                count--;
+                setTimeout(countdown, 1000);
+            } else {
+                // Capture!
+                statusEl.innerHTML = '<i class="bi bi-hourglass-split me-2"></i>Analyzing...';
+                statusEl.className = 'text-center py-3 text-info';
+
+                // Get video element and capture frame
+                const video = document.querySelector('#qrScannerReader video');
+                if (video) {
+                    const canvas = document.createElement('canvas');
+                    canvas.width = video.videoWidth;
+                    canvas.height = video.videoHeight;
+                    const ctx = canvas.getContext('2d');
+                    ctx.drawImage(video, 0, 0);
+
+                    // Stop the scanner before file scan (prevents conflicts)
+                    const scanner = this._qrScanner;
+                    scanner.stop().then(() => {
+                        canvas.toBlob((blob) => {
+                            const file = new File([blob], 'capture.png', { type: 'image/png' });
+                            scanner.scanFile(file, true)
+                                .then((decodedText) => {
+                                    this.onQrCodeDetected(decodedText);
+                                })
+                                .catch((err) => {
+                                    statusEl.innerHTML = '<i class="bi bi-x-circle text-danger me-2"></i>No QR code found. Try again.';
+                                    statusEl.className = 'text-center py-3 text-danger';
+                                    if (captureBtn) captureBtn.disabled = false;
+                                    // Restart the scanner
+                                    this.startQrScanner();
+                                });
+                        }, 'image/png');
+                    }).catch(() => {
+                        statusEl.innerHTML = '<i class="bi bi-x-circle text-danger me-2"></i>Scanner error';
+                        statusEl.className = 'text-center py-3 text-danger';
+                        if (captureBtn) captureBtn.disabled = false;
+                    });
+                } else {
+                    statusEl.innerHTML = '<i class="bi bi-x-circle text-danger me-2"></i>Camera not ready';
+                    statusEl.className = 'text-center py-3 text-danger';
+                    if (captureBtn) captureBtn.disabled = false;
+                }
+            }
+        };
+        countdown();
+    },
+
+    /**
+     * Stop the QR scanner
+     */
+    stopQrScanner() {
+        if (this._qrScanner) {
+            this._qrScanner.stop().then(() => {
+                this._qrScanner.clear();
+                this._qrScanner = null;
+            }).catch((err) => {
+                console.log('Scanner stop error:', err);
+            });
+        }
+    },
+
+    /**
+     * Handle detected QR code
+     * @param {string} text - Decoded QR text
+     */
+    onQrCodeDetected(text) {
+        // Update status
+        const statusEl = document.getElementById('qrScannerStatus');
+        if (statusEl) {
+            statusEl.innerHTML = '<i class="bi bi-check-circle text-success me-2"></i>QR code detected!';
+            statusEl.className = 'text-center py-3 text-success';
+        }
+
+        // Close modal after brief delay
+        setTimeout(() => {
+            this._qrScannerModal?.hide();
+
+            // Call callback
+            if (this._qrScannerCallback) {
+                this._qrScannerCallback(text);
+            }
+        }, 500);
+    },
+
+    /**
+     * Add camera scan button to an input field
+     * @param {string} inputId - ID of the input field
+     * @param {string} title - Modal title
+     * @param {Function} validator - Optional validation function for scanned text
+     */
+    addCameraScanButton(inputId, title = 'Scan QR Code', validator = null) {
+        const input = document.getElementById(inputId);
+        if (!input) return;
+
+        // Create button
+        const btn = document.createElement('button');
+        btn.type = 'button';
+        btn.className = 'btn btn-outline-secondary';
+        btn.innerHTML = '<i class="bi bi-camera"></i>';
+        btn.title = 'Scan QR code with camera';
+
+        btn.addEventListener('click', () => {
+            this.showQrScanner((text) => {
+                // Validate if validator provided
+                if (validator && !validator(text)) {
+                    alert('Invalid QR code format');
+                    return;
+                }
+                // Set input value
+                input.value = text;
+                // Trigger input event for formatting
+                input.dispatchEvent(new Event('input', { bubbles: true }));
+            }, title);
+        });
+
+        // Wrap input in input-group if not already
+        const parent = input.parentElement;
+        if (!parent.classList.contains('input-group')) {
+            const wrapper = document.createElement('div');
+            wrapper.className = 'input-group';
+            parent.insertBefore(wrapper, input);
+            wrapper.appendChild(input);
+            wrapper.appendChild(btn);
+        } else {
+            parent.appendChild(btn);
+        }
+    },
+
     // ========================================================================
     // INITIALIZATION HELPERS
     // ========================================================================
@@ -1111,6 +1505,39 @@ const Stegasoo = {
             generateBtnId: 'channelKeyGenerate'
         });
 
+        // Webcam QR scanning for channel key (v4.1.5)
+        document.getElementById('channelKeyScan')?.addEventListener('click', () => {
+            this.showQrScanner((text) => {
+                const input = document.getElementById('channelKeyInput');
+                if (input) {
+                    const clean = text.replace(/[^A-Za-z0-9]/g, '').toUpperCase();
+                    input.value = clean.length === 32 ? clean.match(/.{4}/g).join('-') : text.toUpperCase();
+                    input.dispatchEvent(new Event('input', { bubbles: true }));
+                }
+            }, 'Scan Channel Key');
+        });
+
+        // Webcam QR scanning for RSA key (v4.1.5)
+        document.getElementById('rsaQrWebcam')?.addEventListener('click', () => {
+            this.showQrScanner((text) => {
+                // Check for raw PEM or compressed format (STEGASOO-Z: prefix)
+                const isRawPem = text.includes('-----BEGIN') && text.includes('KEY-----');
+                const isCompressed = text.startsWith('STEGASOO-Z:');
+                if (isRawPem || isCompressed) {
+                    // Valid RSA key data scanned
+                    document.getElementById('rsaKeyPem').value = text;
+                    // Show success in drop zone
+                    const dropZone = document.getElementById('qrDropZone');
+                    const label = dropZone?.querySelector('.drop-zone-label');
+                    if (label) {
+                        label.innerHTML = '<i class="bi bi-check-circle text-success fs-4 d-block mb-1"></i><span class="text-success small">RSA Key scanned successfully</span>';
+                    }
+                } else {
+                    alert('QR code does not contain a valid RSA key');
+                }
+            }, 'Scan RSA Key QR');
+        });
+
         // Form submission with async progress tracking (v4.1.2)
         const form = document.getElementById('encodeForm');
         const btn = document.getElementById('encodeBtn');
@@ -1136,7 +1563,7 @@ const Stegasoo = {
         this.initRsaMethodToggle();
         this.initDropZones();
         this.initClipboardPaste(['input[name="stego_image"]', 'input[name="reference_photo"]']);
-        this.initQrCropAnimation('rsaKeyQrInput');
+        this.initQrCropAnimation('rsaQrInput');
         this.initCollapseChevrons();
         this.initPassphraseFontResize();
         
@@ -1148,28 +1575,56 @@ const Stegasoo = {
             serverInfoId: 'channelServerInfoDec'
         });
 
-        // Form submission with channel key validation and mode display
+        // Webcam QR scanning for channel key (v4.1.5)
+        document.getElementById('channelKeyScanDec')?.addEventListener('click', () => {
+            this.showQrScanner((text) => {
+                const input = document.getElementById('channelKeyInputDec');
+                if (input) {
+                    const clean = text.replace(/[^A-Za-z0-9]/g, '').toUpperCase();
+                    input.value = clean.length === 32 ? clean.match(/.{4}/g).join('-') : text.toUpperCase();
+                    input.dispatchEvent(new Event('input', { bubbles: true }));
+                }
+            }, 'Scan Channel Key');
+        });
+
+        // Webcam QR scanning for RSA key (v4.1.5)
+        document.getElementById('rsaQrWebcam')?.addEventListener('click', () => {
+            this.showQrScanner((text) => {
+                // Check for raw PEM or compressed format (STEGASOO-Z: prefix)
+                const isRawPem = text.includes('-----BEGIN') && text.includes('KEY-----');
+                const isCompressed = text.startsWith('STEGASOO-Z:');
+                if (isRawPem || isCompressed) {
+                    // Valid RSA key data scanned
+                    document.getElementById('rsaKeyPem').value = text;
+                    // Show success in drop zone
+                    const dropZone = document.getElementById('qrDropZone');
+                    const label = dropZone?.querySelector('.drop-zone-label');
+                    if (label) {
+                        label.innerHTML = '<i class="bi bi-check-circle text-success fs-4 d-block mb-1"></i><span class="text-success small">RSA Key scanned successfully</span>';
+                    }
+                } else {
+                    alert('QR code does not contain a valid RSA key');
+                }
+            }, 'Scan RSA Key QR');
+        });
+
+        // Form submission with async progress tracking (v4.1.5)
         const form = document.getElementById('decodeForm');
         const btn = document.getElementById('decodeBtn');
         form?.addEventListener('submit', (e) => {
-            if (!this.validateChannelKeyOnSubmit(form, 'channelSelectDec', 'channelKeyInputDec')) {
             e.preventDefault();
+
+            if (!this.validateChannelKeyOnSubmit(form, 'channelSelectDec', 'channelKeyInputDec')) {
                 return false;
             }
-            const selectedMode = document.querySelector('input[name="embed_mode"]:checked')?.value || 'auto';
+
             if (btn) {
                 btn.disabled = true;
-                const startTime = Date.now();
+                btn.innerHTML = '<span class="spinner-border spinner-border-sm me-2"></span>Starting...';
-                const updateTimer = () => {
-                    const elapsed = Math.floor((Date.now() - startTime) / 1000);
-                    const mins = Math.floor(elapsed / 60);
-                    const secs = elapsed % 60;
-                    const timeStr = mins > 0 ? `${mins}:${secs.toString().padStart(2, '0')}` : `${secs}s`;
-                    btn.innerHTML = `<span class="spinner-border spinner-border-sm me-2"></span>Decoding (${selectedMode.toUpperCase()})... ${timeStr}`;
-                };
-                updateTimer();
-                setInterval(updateTimer, 1000);
             }
+
+            // Use async submission with progress tracking
+            this.submitDecodeAsync(form, btn);
         });
     },
     

frontends/web/stego_worker.py

@@ -136,14 +136,33 @@ def encode_operation(params: dict) -> dict:
     }
 
 
+def _write_decode_progress(progress_file: str | None, percent: int, phase: str) -> None:
+    """Write decode progress to file."""
+    if not progress_file:
+        return
+    try:
+        import json
+        with open(progress_file, "w") as f:
+            json.dump({"percent": percent, "phase": phase}, f)
+    except Exception:
+        pass  # Best effort
+
+
 def decode_operation(params: dict) -> dict:
     """Handle decode operation."""
     from stegasoo import decode
 
+    progress_file = params.get("progress_file")
+
+    # Progress: starting
+    _write_decode_progress(progress_file, 5, "reading")
+
     # Decode base64 inputs
     stego_data = base64.b64decode(params["stego_b64"])
     reference_data = base64.b64decode(params["reference_b64"])
 
+    _write_decode_progress(progress_file, 15, "reading")
+
     # Optional RSA key
     rsa_key_data = None
     if params.get("rsa_key_b64"):
@@ -152,6 +171,8 @@ def decode_operation(params: dict) -> dict:
     # Resolve channel key (v4.0.0)
     resolved_channel_key = _resolve_channel_key(params.get("channel_key", "auto"))
 
+    _write_decode_progress(progress_file, 25, "extracting")
+
     # Call decode with correct parameter names
     result = decode(
         stego_image=stego_data,
@@ -164,6 +185,8 @@ def decode_operation(params: dict) -> dict:
         channel_key=resolved_channel_key,  # v4.0.0
     )
 
+    _write_decode_progress(progress_file, 90, "finalizing")
+
     if result.is_file:
         return {
             "success": True,

frontends/web/subprocess_stego.py

@@ -314,6 +314,8 @@ class SubprocessStego:
         # Channel key (v4.0.0)
         channel_key: str | None = "auto",
         timeout: int | None = None,
+        # Progress tracking (v4.1.5)
+        progress_file: str | None = None,
     ) -> DecodeResult:
         """
         Decode a message or file from a stego image.
@@ -328,6 +330,7 @@ class SubprocessStego:
             embed_mode: 'auto', 'lsb', or 'dct'
             channel_key: 'auto' (server config), 'none' (public), or explicit key (v4.0.0)
             timeout: Operation timeout in seconds
+            progress_file: Path to write progress updates (v4.1.5)
 
         Returns:
             DecodeResult with message or file_data on success
@@ -340,6 +343,7 @@ class SubprocessStego:
             "pin": pin,
             "embed_mode": embed_mode,
             "channel_key": channel_key,  # v4.0.0
+            "progress_file": progress_file,  # v4.1.5
         }
 
         if rsa_key_data:

frontends/web/temp_storage.py

@@ -14,8 +14,6 @@ It does NOT touch instance/ (auth database) or any other directories.
 """
 
 import json
-import os
-import shutil
 import time
 from pathlib import Path
 from threading import Lock

frontends/web/templates/account.html

@@ -177,9 +177,16 @@
                                    placeholder="Key name" required maxlength="50">
                         </div>
                         <div class="col-7">
-                            <input type="text" name="channel_key" class="form-control form-control-sm font-monospace"
+                            <div class="input-group input-group-sm">
-                                   placeholder="Channel key (32 hex chars)" required
+                                <input type="text" name="channel_key" id="channelKeyInput"
-                                   pattern="[0-9a-fA-F\-]{32,39}" title="32 hex characters">
+                                       class="form-control font-monospace"
+                                       placeholder="XXXX-XXXX-..." required
+                                       pattern="[A-Za-z0-9]{4}(-[A-Za-z0-9]{4}){7}">
+                                <button type="button" class="btn btn-outline-secondary" id="scanChannelKeyBtn"
+                                        title="Scan QR code with camera">
+                                    <i class="bi bi-camera"></i>
+                                </button>
+                            </div>
                         </div>
                     </div>
                     <button type="submit" class="btn btn-sm btn-outline-primary">
@@ -254,12 +261,34 @@
 
 {% block scripts %}
 <script src="{{ url_for('static', filename='js/auth.js') }}"></script>
+<script src="{{ url_for('static', filename='js/stegasoo.js') }}"></script>
 {% if is_admin %}
 <script src="https://cdn.jsdelivr.net/npm/qrcode@1.5.3/build/qrcode.min.js"></script>
 {% endif %}
 <script>
 StegasooAuth.initPasswordConfirmation('accountForm', 'newPasswordInput', 'newPasswordConfirmInput');
 
+// Webcam QR scanning for channel key input (v4.1.5)
+document.getElementById('scanChannelKeyBtn')?.addEventListener('click', function() {
+    Stegasoo.showQrScanner((text) => {
+        const input = document.getElementById('channelKeyInput');
+        if (input) {
+            // Clean and format the key
+            const clean = text.replace(/[^A-Za-z0-9]/g, '').toUpperCase();
+            if (clean.length === 32) {
+                input.value = clean.match(/.{4}/g).join('-');
+            } else {
+                input.value = text.toUpperCase();
+            }
+        }
+    }, 'Scan Channel Key');
+});
+
+// Format channel key input as user types
+document.getElementById('channelKeyInput')?.addEventListener('input', function() {
+    Stegasoo.formatChannelKeyInput(this);
+});
+
 function renameKey(keyId, currentName) {
     document.getElementById('renameInput').value = currentName;
     document.getElementById('renameForm').action = '/account/keys/' + keyId + '/rename';

frontends/web/templates/base.html

@@ -101,6 +101,8 @@
     </footer>
 
     <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/js/bootstrap.bundle.min.js"></script>
+    <!-- QR Code scanning library (v4.1.5) -->
+    <script src="https://unpkg.com/html5-qrcode@2.3.8/html5-qrcode.min.js"></script>
     <script>
     // Initialize toasts (auto-hide after delay)
     document.querySelectorAll('.toast').forEach(el => new bootstrap.Toast(el));

frontends/web/templates/decode.html

@@ -4,6 +4,74 @@
 
 {% block content %}
 <style>
+/* Accordion styling */
+.step-accordion .accordion-button {
+    background: rgba(30, 40, 50, 0.6);
+    color: #fff;
+    padding: 0.75rem 1rem;
+    border-left: 3px solid transparent;
+    transition: all 0.3s ease;
+}
+.step-accordion .accordion-button:not(.collapsed) {
+    background: linear-gradient(90deg, rgba(99, 179, 237, 0.15) 0%, rgba(40, 50, 60, 0.8) 40%, rgba(40, 50, 60, 0.8) 100%);
+    color: #fff;
+    box-shadow: inset 0 1px 0 rgba(99, 179, 237, 0.1);
+    border-left: 3px solid rgba(99, 179, 237, 0.6);
+}
+.step-accordion .accordion-button::after {
+    filter: invert(1);
+}
+.step-accordion .accordion-body {
+    background: rgba(30, 40, 50, 0.4);
+    padding: 1rem;
+}
+.step-accordion .accordion-item {
+    border-color: rgba(255,255,255,0.1);
+    background: transparent;
+}
+.step-accordion .accordion-item:first-child .accordion-button {
+    border-radius: 0;
+}
+.step-accordion .accordion-item:last-child .accordion-button.collapsed {
+    border-radius: 0;
+}
+.step-summary {
+    font-size: 0.8rem;
+    color: rgba(255,255,255,0.5);
+    margin-left: auto;
+    padding-right: 1rem;
+    white-space: nowrap;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    max-width: 50%;
+}
+.step-summary.has-content {
+    color: rgba(99, 179, 237, 0.8);
+}
+.step-title {
+    display: flex;
+    align-items: center;
+    gap: 0.5rem;
+}
+.step-number {
+    background: rgba(246, 173, 85, 0.2);
+    color: #f6ad55;
+    width: 1.5rem;
+    height: 1.5rem;
+    border-radius: 50%;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    font-size: 0.75rem;
+    font-weight: bold;
+    border: 1px solid rgba(246, 173, 85, 0.3);
+}
+.step-number.complete {
+    background: rgba(72, 187, 120, 0.2);
+    color: #48bb78;
+    border-color: rgba(72, 187, 120, 0.3);
+}
+
 /* Glowing passphrase input */
 .passphrase-input {
     background: rgba(30, 40, 50, 0.8) !important;
@@ -13,20 +81,17 @@
     font-size: 1.1rem;
     letter-spacing: 0.5px;
     padding: 12px 16px;
-    transition: border-color 0.3s ease, box-shadow 0.3s ease, background 0.3s ease;
+    transition: border-color 0.3s ease, box-shadow 0.3s ease;
 }
-
 .passphrase-input:focus {
     border-color: rgba(99, 179, 237, 0.8) !important;
-    box-shadow: 0 0 20px rgba(99, 179, 237, 0.4), 0 0 40px rgba(99, 179, 237, 0.2) !important;
+    box-shadow: 0 0 20px rgba(99, 179, 237, 0.4) !important;
-    background: rgba(30, 40, 50, 0.95) !important;
 }
-
 .passphrase-input::placeholder {
     color: rgba(99, 179, 237, 0.4);
 }
 
-/* Glowing PIN input */
+/* PIN input */
 .pin-input-container .form-control {
     background: rgba(30, 40, 50, 0.8) !important;
     border: 2px solid rgba(246, 173, 85, 0.3) !important;
@@ -35,18 +100,10 @@
     font-size: 1.2rem;
     letter-spacing: 3px;
     text-align: center;
-    transition: all 0.3s ease;
 }
-
 .pin-input-container .form-control:focus {
     border-color: rgba(246, 173, 85, 0.8) !important;
-    box-shadow: 0 0 20px rgba(246, 173, 85, 0.4), 0 0 40px rgba(246, 173, 85, 0.2) !important;
+    box-shadow: 0 0 20px rgba(246, 173, 85, 0.4) !important;
-    background: rgba(30, 40, 50, 0.95) !important;
-}
-
-.pin-input-container .form-control::placeholder {
-    color: rgba(246, 173, 85, 0.4);
-    letter-spacing: 1px;
 }
 
 /* QR Crop Animation */
@@ -55,8 +112,12 @@
     overflow: hidden;
     border-radius: 8px;
     background: rgba(0, 0, 0, 0.3);
+    width: 100%;
+    display: flex;
+    justify-content: center;
+    align-items: center;
+    min-height: 120px;
 }
-
 .qr-crop-container img {
     display: block;
     max-height: 180px;
@@ -65,15 +126,10 @@
     margin: 0 auto;
     transition: all 0.6s cubic-bezier(0.4, 0, 0.2, 1);
 }
-
+.qr-crop-container .qr-original { opacity: 1; }
-.qr-crop-container .qr-original {
-    opacity: 1;
-}
-
 .qr-crop-container .qr-cropped {
     position: absolute;
-    top: 50%;
+    top: 50%; left: 50%;
-    left: 50%;
     transform: translate(-50%, -50%) scale(0.3);
     opacity: 0;
     max-height: 160px;
@@ -81,30 +137,15 @@
     min-height: 140px;
     object-fit: contain;
 }
-
 .qr-crop-container.scan-complete .qr-original {
     opacity: 0;
     transform: scale(1.1);
     filter: blur(4px);
 }
-
 .qr-crop-container.scan-complete .qr-cropped {
     opacity: 1;
     transform: translate(-50%, -50%) scale(1);
 }
-
-.qr-crop-container .crop-badge {
-    position: absolute;
-    bottom: 4px;
-    right: 4px;
-    font-size: 0.65rem;
-    opacity: 0;
-    transition: opacity 0.3s ease 0.4s;
-}
-
-.qr-crop-container.scan-complete .crop-badge {
-    opacity: 1;
-}
 </style>
 
 <div class="row justify-content-center">
@@ -113,7 +154,7 @@
             <div class="card-header">
                 <h5 class="mb-0"><i class="bi bi-unlock-fill me-2"></i>Decode Secret Message or File</h5>
             </div>
-            <div class="card-body">
+            <div class="card-body {% if not decoded_message and not decoded_file %}p-0{% endif %}">
                 {% if decoded_message %}
                 <!-- Text Message Result -->
                 <div class="alert alert-success">
@@ -161,46 +202,48 @@
                 {% else %}
                 <!-- Decode Form -->
                 <form method="POST" enctype="multipart/form-data" id="decodeForm">
+
+                    <div class="accordion step-accordion" id="decodeAccordion">
+
+                        <!-- ================================================================
+                             STEP 1: IMAGES & MODE
+                             ================================================================ -->
+                        <div class="accordion-item">
+                            <h2 class="accordion-header">
+                                <button class="accordion-button" type="button" data-bs-toggle="collapse" data-bs-target="#stepImages">
+                                    <span class="step-title">
+                                        <span class="step-number" id="stepImagesNumber">1</span>
+                                        <i class="bi bi-images me-1"></i> Images & Mode
+                                    </span>
+                                    <span class="step-summary" id="stepImagesSummary">Select reference & stego</span>
+                                </button>
+                            </h2>
+                            <div id="stepImages" class="accordion-collapse collapse show" data-bs-parent="#decodeAccordion">
+                                <div class="accordion-body">
+
                                     <div class="row">
                                         <div class="col-md-6 mb-3">
                                             <label class="form-label">
                                                 <i class="bi bi-image me-1"></i> Reference Photo
                                             </label>
                                             <div class="drop-zone scan-container" id="refDropZone">
-                                <input type="file" name="reference_photo" accept="image/*" required>
+                                                <input type="file" name="reference_photo" accept="image/*" required id="refPhotoInput">
                                                 <div class="drop-zone-label">
                                                     <i class="bi bi-cloud-arrow-up fs-3 d-block mb-2 text-muted"></i>
-                                    <span class="text-muted">Drop image or click to browse</span>
+                                                    <span class="text-muted">Drop image or click</span>
                                                 </div>
                                                 <img class="drop-zone-preview d-none" id="refPreview">
-                                <!-- Scan overlay elements -->
+                                                <div class="scan-overlay"><div class="scan-grid"></div><div class="scan-line"></div></div>
-                                <div class="scan-overlay">
-                                    <div class="scan-grid"></div>
-                                    <div class="scan-line"></div>
-                                </div>
-                                <!-- Corner brackets (shown after scan) -->
                                                 <div class="scan-corners">
-                                    <div class="scan-corner tl"></div>
+                                                    <div class="scan-corner tl"></div><div class="scan-corner tr"></div>
-                                    <div class="scan-corner tr"></div>
+                                                    <div class="scan-corner bl"></div><div class="scan-corner br"></div>
-                                    <div class="scan-corner bl"></div>
-                                    <div class="scan-corner br"></div>
                                                 </div>
-                                <!-- Data panel (shown after scan) -->
                                                 <div class="scan-data-panel">
-                                    <div class="scan-data-filename">
+                                                    <div class="scan-data-filename"><i class="bi bi-check-circle-fill"></i><span id="refFileName">image.jpg</span></div>
-                                        <i class="bi bi-check-circle-fill"></i>
+                                                    <div class="scan-data-row"><span class="scan-status-badge">Hash Acquired</span><span class="scan-data-value" id="refFileSize">--</span></div>
-                                        <span id="refFileName">image.jpg</span>
-                                    </div>
-                                    <div class="scan-data-row">
-                                        <span class="scan-status-badge">Hash Acquired</span>
-                                        <span class="scan-data-value" id="refFileSize">--</span>
-                                    </div>
-                                    <div class="scan-hash-preview" id="refHashPreview">SHA256: ················</div>
                                                 </div>
                                             </div>
-                            <div class="form-text">
+                                            <div class="form-text">Same reference photo used for encoding</div>
-                                The same reference photo used for encoding
-                            </div>
                                         </div>
 
                                         <div class="col-md-6 mb-3">
@@ -208,124 +251,85 @@
                                                 <i class="bi bi-file-earmark-image me-1"></i> Stego Image
                                             </label>
                                             <div class="drop-zone pixel-container" id="stegoDropZone">
-                                <input type="file" name="stego_image" accept="image/*" required>
+                                                <input type="file" name="stego_image" accept="image/*" required id="stegoInput">
                                                 <div class="drop-zone-label">
                                                     <i class="bi bi-cloud-arrow-up fs-3 d-block mb-2 text-muted"></i>
-                                    <span class="text-muted">Drop image or click to browse</span>
+                                                    <span class="text-muted">Drop image or click</span>
                                                 </div>
                                                 <img class="drop-zone-preview d-none" id="stegoPreview">
-                                <!-- Pixel blocks overlay - populated by JS -->
                                                 <div class="pixel-blocks"></div>
-                                <!-- Pixel scan line -->
                                                 <div class="pixel-scan-line"></div>
-                                <!-- Corner brackets -->
                                                 <div class="pixel-corners">
-                                    <div class="pixel-corner tl"></div>
+                                                    <div class="pixel-corner tl"></div><div class="pixel-corner tr"></div>
-                                    <div class="pixel-corner tr"></div>
+                                                    <div class="pixel-corner bl"></div><div class="pixel-corner br"></div>
-                                    <div class="pixel-corner bl"></div>
-                                    <div class="pixel-corner br"></div>
                                                 </div>
-                                <!-- Data panel -->
                                                 <div class="pixel-data-panel">
-                                    <div class="pixel-data-filename">
+                                                    <div class="pixel-data-filename"><i class="bi bi-check-circle-fill"></i><span id="stegoFileName">image.png</span></div>
-                                        <i class="bi bi-check-circle-fill"></i>
+                                                    <div class="pixel-data-row"><span class="pixel-status-badge">Stego Loaded</span><span class="pixel-data-value" id="stegoFileSize">--</span></div>
-                                        <span id="stegoFileName">image.png</span>
+                                                    <div class="pixel-dimensions" id="stegoDims">-- x -- px</div>
                                                 </div>
-                                    <div class="pixel-data-row">
-                                        <span class="pixel-status-badge">Stego Loaded</span>
-                                        <span class="pixel-data-value" id="stegoFileSize">--</span>
                                             </div>
-                                    <div class="pixel-dimensions" id="stegoDims">-- × -- px</div>
+                                            <div class="form-text">Image containing the hidden message</div>
                                         </div>
                                     </div>
+
+                                    <!-- Extraction Mode -->
+                                    <label class="form-label"><i class="bi bi-cpu me-1"></i> Extraction Mode</label>
+                                    <div class="d-flex gap-2 mb-2">
+                                        <label class="mode-btn flex-fill active" id="autoModeCard" for="modeAuto">
+                                            <input class="form-check-input" type="radio" name="embed_mode" id="modeAuto" value="auto" checked>
+                                            <i class="bi bi-magic text-success ms-2"></i>
+                                            <span class="ms-2"><strong>Auto</strong> <span class="text-muted d-none d-sm-inline">· Try both</span></span>
+                                        </label>
+                                        <label class="mode-btn flex-fill" id="lsbModeCard" for="modeLsb">
+                                            <input class="form-check-input" type="radio" name="embed_mode" id="modeLsb" value="lsb">
+                                            <i class="bi bi-grid-3x3-gap text-primary ms-2"></i>
+                                            <span class="ms-2"><strong>LSB</strong> <span class="text-muted d-none d-sm-inline">· Email</span></span>
+                                        </label>
+                                        <label class="mode-btn flex-fill {% if not has_dct %}opacity-50{% endif %}" id="dctModeCard" for="modeDct">
+                                            <input class="form-check-input" type="radio" name="embed_mode" id="modeDct" value="dct" {% if not has_dct %}disabled{% endif %}>
+                                            <i class="bi bi-soundwave text-warning ms-2"></i>
+                                            <span class="ms-2"><strong>DCT</strong> <span class="text-muted d-none d-sm-inline">· Social</span></span>
+                                        </label>
+                                    </div>
                                     <div class="form-text">
-                                The image containing the hidden message/file
+                                        <i class="bi bi-lightbulb me-1"></i><strong>Auto</strong> tries LSB first, then DCT.
+                                    </div>
+
                                 </div>
                             </div>
                         </div>
 
-                    <div class="mb-3">
+                        <!-- ================================================================
-                        <label class="form-label">
+                             STEP 2: SECURITY
-                            <i class="bi bi-chat-quote me-1"></i> Passphrase
+                             ================================================================ -->
-                        </label>
+                        <div class="accordion-item">
-                        <input type="text" name="passphrase" id="passphraseInput" class="form-control passphrase-input" 
+                            <h2 class="accordion-header">
-                               placeholder="e.g., correct horse battery staple" required>
+                                <button class="accordion-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#stepSecurity">
-                        <div class="form-text">
+                                    <span class="step-title">
-                            The passphrase used during encoding (typically 4 words)
+                                        <span class="step-number" id="stepSecurityNumber">2</span>
-                        </div>
+                                        <i class="bi bi-shield-lock me-1"></i> Security
-                    </div>
+                                    </span>
-                    
+                                    <span class="step-summary" id="stepSecuritySummary">Passphrase & keys</span>
-                    <hr class="my-4">
-                    
-                    <h6 class="text-muted mb-3">
-                        SECURITY FACTORS 
-                        <span class="text-warning small">(provide same factors used during encoding)</span>
-                    </h6>
-                    
-                    <div class="mb-3">
-                      <div class="security-box">
-                        <label class="form-label">
-                            <i class="bi bi-file-earmark-lock me-1"></i> RSA Key
-                        </label>
-
-                        <!-- RSA Input Method Toggle -->
-                        <div class="btn-group w-100 mb-2" role="group">
-                            <input type="radio" class="btn-check" name="rsa_input_method" id="rsaMethodFile" value="file" checked>
-                            <label class="btn btn-outline-secondary btn-sm" for="rsaMethodFile">
-                                <i class="bi bi-file-earmark me-1"></i>.pem File
-                            </label>
-
-                            <input type="radio" class="btn-check" name="rsa_input_method" id="rsaMethodQr" value="qr">
-                            <label class="btn btn-outline-secondary btn-sm" for="rsaMethodQr">
-                                <i class="bi bi-qr-code me-1"></i>QR Code
-                            </label>
-                        </div>
-
-                        <!-- .pem File Input -->
-                        <div id="rsaFileSection">
-                            <input type="file" name="rsa_key" class="form-control form-control-sm" id="rsaKeyInput" accept=".pem,.key,application/x-pem-file">
-                        </div>
-
-                        <!-- QR Code Input -->
-                        <div id="rsaQrSection" class="d-none">
-                            <div class="drop-zone p-3" id="qrDropZone">
-                                <input type="file" name="rsa_key_qr" accept="image/*" id="rsaKeyQrInput">
-                                <div class="drop-zone-label text-center">
-                                    <i class="bi bi-qr-code-scan fs-4 d-block text-muted mb-1"></i>
-                                    <span class="text-muted small">Drop QR image or click to browse</span>
-                                </div>
-                                <!-- Crop animation container -->
-                                <div class="qr-scan-container qr-crop-container d-none" id="qrCropContainer">
-                                    <img class="qr-original" id="qrOriginal" alt="Original">
-                                    <img class="qr-cropped" id="qrCropped" alt="Cropped QR">
-                                    <!-- Data panel -->
-                                    <div class="qr-data-panel">
-                                        <div class="qr-data-filename">
-                                            <i class="bi bi-check-circle-fill"></i>
-                                            <span>RSA Key loaded</span>
-                                        </div>
-                                        <div class="qr-data-row">
-                                            <span class="qr-status-badge">RSA Key</span>
-                                            <span class="qr-data-value">--</span>
-                                        </div>
-                                    </div>
-                                </div>
-                            </div>
-                        </div>
-
-                        <!-- Key Password (always visible) -->
-                        <div class="input-group input-group-sm mt-2">
-                            <input type="password" name="rsa_password" class="form-control" id="rsaPasswordInput" placeholder="Key password (if encrypted)">
-                            <button class="btn btn-outline-secondary" type="button" data-toggle-password="rsaPasswordInput">
-                                <i class="bi bi-eye"></i>
                                 </button>
-                        </div>
+                            </h2>
-                      </div>
+                            <div id="stepSecurity" class="accordion-collapse collapse" data-bs-parent="#decodeAccordion">
+                                <div class="accordion-body">
+
+                                    <!-- Passphrase -->
+                                    <div class="mb-3">
+                                        <label class="form-label"><i class="bi bi-chat-quote me-1"></i> Passphrase</label>
+                                        <input type="text" name="passphrase" class="form-control passphrase-input"
+                                               placeholder="e.g., apple forest thunder mountain" required id="passphraseInput">
+                                        <div class="form-text">The passphrase used during encoding</div>
                                     </div>
 
-                    <!-- PIN + Channel Row -->
+                                    <hr class="my-3 opacity-25">
+                                    <div class="small text-muted mb-2">Provide same factors used during encoding</div>
+
                                     <div class="row">
-                        <div class="col-md-6 mb-3">
+                                        <!-- PIN -->
+                                        <div class="col-md-6 mb-2">
                                             <div class="security-box h-100">
                                                 <label class="form-label"><i class="bi bi-123 me-1"></i> PIN</label>
                                                 <div class="input-group pin-input-container">
@@ -334,103 +338,75 @@
                                                         <i class="bi bi-eye"></i>
                                                     </button>
                                                 </div>
-                            <div class="form-text">If PIN was used during encoding</div>
                                                 </div>
                                         </div>
 
-                        <div class="col-md-6 mb-3">
+                                        <!-- Channel -->
+                                        <div class="col-md-6 mb-2">
                                             <div class="security-box h-100">
-                            <label class="form-label">
+                                                <label class="form-label"><i class="bi bi-broadcast me-1"></i> Channel</label>
-                                <i class="bi bi-broadcast me-1"></i> Channel
+                                                <select class="form-select form-select-sm" name="channel_key" id="channelSelectDec">
-                                <span class="badge bg-info ms-1">v4.1</span>
+                                                    <option value="auto" selected>Auto{% if channel_configured %} (Server){% endif %}</option>
-                                <a href="/about#channel-keys" class="text-muted ms-1" title="Learn about channels"><i class="bi bi-info-circle"></i></a>
-                            </label>
-
-                            <select class="form-select" name="channel_key" id="channelSelectDec">
-                                <option value="auto" selected>Auto{% if channel_configured %} (Server Key){% endif %}</option>
                                                     <option value="none">Public</option>
                                                     {% if saved_channel_keys %}
                                                     <optgroup label="Saved Keys">
                                                         {% for key in saved_channel_keys %}
-                                    <option value="{{ key.channel_key }}" data-key-id="{{ key.id }}">{{ key.name }} ({{ key.channel_key[:4] }}...)</option>
+                                                        <option value="{{ key.channel_key }}">{{ key.name }}</option>
                                                         {% endfor %}
                                                     </optgroup>
                                                     {% endif %}
                                                     <option value="custom">Custom...</option>
                                                 </select>
-
-                            <!-- Server channel indicator (compact) -->
-                            <div class="small text-success mt-2 {% if not channel_configured %}d-none{% endif %}" id="channelServerInfoDec" data-fingerprint="{{ (channel_fingerprint[:4] if channel_fingerprint else '') }}-••••-···-••••-{{ channel_fingerprint[-4:] if channel_fingerprint else '' }}">
-                                {% if channel_configured and channel_fingerprint %}
-                                <i class="bi bi-shield-lock me-1"></i>
-                                Server: <code>{{ channel_fingerprint[:4] }}-••••-···-••••-{{ channel_fingerprint[-4:] }}</code>
-                                {% endif %}
-                            </div>
                                             </div>
                                         </div>
                                     </div>
 
-                    <!-- Custom Channel Key Input (shown when Custom selected) -->
+                                    <!-- Custom Channel Key -->
-                    <div class="mb-4 d-none" id="channelCustomInputDec">
+                                    <div class="mb-3 d-none" id="channelCustomInputDec">
                                         <div class="security-box">
                                             <label class="form-label"><i class="bi bi-key me-1"></i> Custom Channel Key</label>
                                             <div class="input-group">
-                                <input type="text" name="channel_key_custom" class="form-control font-monospace"
+                                                <input type="text" name="channel_key_custom" class="form-control form-control-sm font-monospace"
-                                       placeholder="XXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXX"
+                                                       placeholder="XXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXX" id="channelKeyInputDec">
-                                       pattern="[A-Za-z0-9]{4}(-[A-Za-z0-9]{4}){7}"
+                                                <button class="btn btn-outline-secondary btn-sm" type="button" id="channelKeyScanDec" title="Scan QR"><i class="bi bi-camera"></i></button>
-                                       id="channelKeyInputDec">
                                             </div>
                                         </div>
                                     </div>
 
-                    <!-- ================================================================
+                                    <!-- RSA Key -->
-                         ADVANCED OPTIONS (v3.0) - Extraction Mode
+                                    <div class="mb-3">
-                         ================================================================ -->
+                                        <div class="security-box">
-                    <div class="mb-4">
+                                            <label class="form-label"><i class="bi bi-file-earmark-lock me-1"></i> RSA Key <span class="text-muted">(if used)</span></label>
-                        <a class="btn btn-sm btn-outline-secondary w-100" data-bs-toggle="collapse" href="#advancedOptionsDec" role="button" aria-expanded="false">
+                                            <div class="btn-group w-100 mb-2" role="group">
-                            <i class="bi bi-gear me-1"></i> Advanced Options
+                                                <input type="radio" class="btn-check" name="rsa_input_method" id="rsaMethodFile" value="file" checked>
-                            <i class="bi bi-chevron-down ms-1" id="advancedChevronDec"></i>
+                                                <label class="btn btn-outline-secondary btn-sm" for="rsaMethodFile"><i class="bi bi-file-earmark me-1"></i>.pem</label>
-                        </a>
+                                                <input type="radio" class="btn-check" name="rsa_input_method" id="rsaMethodQr" value="qr">
-                        
+                                                <label class="btn btn-outline-secondary btn-sm" for="rsaMethodQr"><i class="bi bi-qr-code me-1"></i>QR</label>
-                        <div class="collapse" id="advancedOptionsDec">
+                                            </div>
-                            <div class="card card-body mt-2 bg-dark border-secondary">
+                                            <div id="rsaFileSection">
-                                
+                                                <input type="file" name="rsa_key" class="form-control form-control-sm" accept=".pem">
-                                <!-- Extraction Mode Selection -->
+                                            </div>
-                                <div class="mb-0">
+                                            <div id="rsaQrSection" class="d-none d-flex flex-column">
-                                    <label class="form-label">
+                                                <input type="hidden" name="rsa_key_pem" id="rsaKeyPem">
-                                        <i class="bi bi-cpu me-1"></i> Extraction Mode
+                                                <div class="drop-zone p-2 w-100" id="qrDropZone">
-                                        <span class="badge bg-info ms-1">v3.0</span>
+                                                    <input type="file" name="rsa_key_qr" accept="image/*" id="rsaQrInput">
-                                    </label>
+                                                    <div class="drop-zone-label text-center">
-                                    
+                                                        <i class="bi bi-qr-code-scan fs-5 d-block text-muted mb-1"></i>
-                                    <div class="d-flex gap-2">
+                                                        <span class="text-muted small">Drop QR image</span>
-                                        <!-- Auto Mode -->
+                                                    </div>
-                                        <label class="mode-btn flex-fill active" id="autoModeCard" for="modeAuto">
+                                                    <div class="qr-scan-container qr-crop-container d-none" id="qrCropContainer">
-                                            <input class="form-check-input" type="radio" name="embed_mode" id="modeAuto" value="auto" checked>
+                                                        <img class="qr-original" id="qrOriginal" alt="Original">
-                                            <i class="bi bi-magic text-success"></i>
+                                                        <img class="qr-cropped" id="qrCropped" alt="Cropped">
-                                            <span class="ms-2"><strong>Auto</strong> <span class="text-muted d-none d-sm-inline">· Try both</span></span>
+                                                    </div>
-                                        </label>
+                                                </div>
-                                        
+                                                <button type="button" class="btn btn-outline-secondary btn-sm w-100 mt-2" id="rsaQrWebcam">
-                                        <!-- LSB Mode -->
+                                                    <i class="bi bi-camera me-1"></i>Scan with Camera
-                                        <label class="mode-btn flex-fill" id="lsbModeCardDec" for="modeLsbDec">
+                                                </button>
-                                            <input class="form-check-input" type="radio" name="embed_mode" id="modeLsbDec" value="lsb">
+                                            </div>
-                                            <i class="bi bi-grid-3x3-gap text-primary"></i>
+                                            <div class="input-group input-group-sm mt-2">
-                                            <span class="ms-2"><strong>LSB</strong> <span class="text-muted d-none d-sm-inline">· Spatial</span></span>
+                                                <input type="password" name="rsa_password" class="form-control" id="rsaPasswordInput" placeholder="Key password (if encrypted)">
-                                        </label>
+                                                <button class="btn btn-outline-secondary" type="button" data-toggle-password="rsaPasswordInput"><i class="bi bi-eye"></i></button>
-                                        
-                                        <!-- DCT Mode -->
-                                        <label class="mode-btn flex-fill {% if not has_dct %}opacity-50{% endif %}" id="dctModeCardDec" for="modeDctDec">
-                                            <input class="form-check-input" type="radio" name="embed_mode" id="modeDctDec" value="dct" {% if not has_dct %}disabled{% endif %}>
-                                            <i class="bi bi-soundwave text-warning"></i>
-                                            <span class="ms-2"><strong>DCT</strong> <span class="text-muted d-none d-sm-inline">· Frequency</span></span>
-                                        </label>
                                             </div>
-                                    
-                                    <div class="form-text mt-2">
-                                        <i class="bi bi-lightbulb me-1"></i>
-                                        <strong>Auto</strong> tries LSB first, then DCT.
-                                        {% if not has_dct %}
-                                        <span class="text-warning ms-2"><i class="bi bi-exclamation-triangle me-1"></i>DCT requires scipy</span>
-                                        {% endif %}
                                         </div>
                                     </div>
 
@@ -438,51 +414,41 @@
                             </div>
                         </div>
 
+                    </div>
+
+                    <!-- Submit Button -->
+                    <div class="p-3">
                         <button type="submit" class="btn btn-primary btn-lg w-100" id="decodeBtn">
                             <i class="bi bi-unlock me-2"></i>Decode
                         </button>
-                </form>
+                    </div>
 
+                </form>
                 {% endif %}
             </div>
         </div>
 
         {% if not decoded_message and not decoded_file %}
+        <!-- Troubleshooting Card -->
         <div class="card mt-4">
             <div class="card-body">
                 <h6 class="text-muted mb-3"><i class="bi bi-question-circle me-2"></i>Troubleshooting</h6>
                 <ul class="list-unstyled text-muted small mb-0">
                     <li class="mb-2">
                         <i class="bi bi-check-circle-fill text-success me-1"></i>
-                        Use the <strong>exact same reference photo</strong> file (byte-for-byte identical)
+                        Use the <strong>exact same reference photo</strong> (byte-for-byte identical)
                     </li>
                     <li class="mb-2">
                         <i class="bi bi-check-circle-fill text-success me-1"></i>
-                        Enter the <strong>exact passphrase</strong> used during encoding (case-sensitive, spacing matters)
+                        Enter the <strong>exact passphrase</strong> used during encoding
-                    </li>
-                    <li class="mb-2">
-                        <i class="bi bi-check-circle-fill text-success me-1"></i>
-                        Provide the <strong>same security factors</strong> (PIN and/or RSA key) used during encoding
                     </li>
                     <li class="mb-2">
                         <i class="bi bi-exclamation-triangle-fill text-warning me-1"></i>
-                        Ensure the stego image hasn't been <strong>resized, cropped, or recompressed</strong>
+                        Ensure the stego image hasn't been <strong>resized or recompressed</strong>
-                    </li>
-                    <li class="mb-2">
-                        <i class="bi bi-exclamation-triangle-fill text-warning me-1"></i>
-                        <strong>Format compatibility:</strong> v4.0 cannot decode messages from v3.1 or earlier (different format)
-                    </li>
-                    <li class="mb-2">
-                        <i class="bi bi-broadcast text-info me-1"></i>
-                        <strong>Channel key:</strong> Use the same channel (Auto/Public/Custom) that was used during encoding
-                    </li>
-                    <li class="mb-2">
-                        <i class="bi bi-info-circle-fill text-info me-1"></i>
-                        If using an RSA key, verify the <strong>password is correct</strong> (if key is encrypted)
                     </li>
                     <li class="mb-0">
                         <i class="bi bi-info-circle-fill text-info me-1"></i>
-                        If auto-detection fails, try specifying <strong>LSB or DCT mode</strong> in Advanced Options
+                        If auto-detection fails, try specifying <strong>LSB or DCT mode</strong>
                     </li>
                 </ul>
             </div>
@@ -495,31 +461,92 @@
 {% block scripts %}
 <script src="{{ url_for('static', filename='js/stegasoo.js') }}"></script>
 <script>
-// Extraction mode button active state toggle
+// ============================================================================
-const extractModeRadios = document.querySelectorAll('input[name="embed_mode"]');
+// ACCORDION SUMMARY UPDATES
-const extractModeBtns = { 
+// ============================================================================
-    'auto': document.getElementById('autoModeCard'), 
-    'lsb': document.getElementById('lsbModeCardDec'), 
-    'dct': document.getElementById('dctModeCardDec') 
-};
 
-extractModeRadios.forEach(radio => {
+function updateImagesSummary() {
+    const ref = document.getElementById('refPhotoInput')?.files[0];
+    const stego = document.getElementById('stegoInput')?.files[0];
+    const mode = document.querySelector('input[name="embed_mode"]:checked')?.value?.toUpperCase() || 'AUTO';
+    const summary = document.getElementById('stepImagesSummary');
+    const stepNum = document.getElementById('stepImagesNumber');
+
+    if (ref && stego) {
+        const refName = ref.name.length > 12 ? ref.name.slice(0, 10) + '..' : ref.name;
+        const stegoName = stego.name.length > 12 ? stego.name.slice(0, 10) + '..' : stego.name;
+        summary.textContent = `${refName} + ${stegoName}, ${mode}`;
+        summary.classList.add('has-content');
+        stepNum.classList.add('complete');
+        stepNum.innerHTML = '<i class="bi bi-check"></i>';
+    } else if (ref || stego) {
+        summary.textContent = ref ? ref.name.slice(0, 15) : stego.name.slice(0, 15);
+        summary.classList.remove('has-content');
+        stepNum.classList.remove('complete');
+        stepNum.textContent = '1';
+    } else {
+        summary.textContent = 'Select reference & stego';
+        summary.classList.remove('has-content');
+        stepNum.classList.remove('complete');
+        stepNum.textContent = '1';
+    }
+}
+
+function updateSecuritySummary() {
+    const passphrase = document.getElementById('passphraseInput')?.value || '';
+    const pin = document.getElementById('pinInput')?.value || '';
+    const rsaFile = document.querySelector('input[name="rsa_key"]')?.files[0];
+    const rsaPem = document.getElementById('rsaKeyPem')?.value || '';
+    const summary = document.getElementById('stepSecuritySummary');
+    const stepNum = document.getElementById('stepSecurityNumber');
+
+    const parts = [];
+    if (passphrase.trim()) parts.push('passphrase');
+    if (pin) parts.push('PIN');
+    if (rsaFile || rsaPem) parts.push('RSA');
+
+    if (parts.length > 0) {
+        summary.textContent = parts.join(' + ');
+        summary.classList.add('has-content');
+        if (passphrase.trim()) {
+            stepNum.classList.add('complete');
+            stepNum.innerHTML = '<i class="bi bi-check"></i>';
+        }
+    } else {
+        summary.textContent = 'Passphrase & keys';
+        summary.classList.remove('has-content');
+        stepNum.classList.remove('complete');
+        stepNum.textContent = '2';
+    }
+}
+
+// Attach listeners
+document.getElementById('refPhotoInput')?.addEventListener('change', updateImagesSummary);
+document.getElementById('stegoInput')?.addEventListener('change', updateImagesSummary);
+document.querySelectorAll('input[name="embed_mode"]').forEach(r => r.addEventListener('change', updateImagesSummary));
+
+document.getElementById('passphraseInput')?.addEventListener('input', updateSecuritySummary);
+document.getElementById('pinInput')?.addEventListener('input', updateSecuritySummary);
+document.querySelector('input[name="rsa_key"]')?.addEventListener('change', updateSecuritySummary);
+
+// ============================================================================
+// MODE SWITCHING
+// ============================================================================
+
+const modeRadios = document.querySelectorAll('input[name="embed_mode"]');
+const modeBtns = { 'auto': document.getElementById('autoModeCard'), 'lsb': document.getElementById('lsbModeCard'), 'dct': document.getElementById('dctModeCard') };
+
+modeRadios.forEach(radio => {
     radio.addEventListener('change', () => {
-        Object.values(extractModeBtns).forEach(btn => btn?.classList.remove('active'));
+        Object.values(modeBtns).forEach(btn => btn?.classList.remove('active'));
-        extractModeBtns[radio.value]?.classList.add('active');
+        modeBtns[radio.value]?.classList.add('active');
     });
 });
 
-// Advanced options chevron
+// ============================================================================
-const advancedOptionsDec = document.getElementById('advancedOptionsDec');
+// LOADING STATE
-advancedOptionsDec?.addEventListener('show.bs.collapse', () => {
+// ============================================================================
-    document.getElementById('advancedChevronDec')?.classList.replace('bi-chevron-down', 'bi-chevron-up');
-});
-advancedOptionsDec?.addEventListener('hide.bs.collapse', () => {
-    document.getElementById('advancedChevronDec')?.classList.replace('bi-chevron-up', 'bi-chevron-down');
-});
 
-// Loading state for decode button
 Stegasoo.initFormLoading('decodeForm', 'decodeBtn', 'Decoding...');
 </script>
 {% endblock %}

instance/.secret_key

@@ -1 +0,0 @@
-6a7378172fc0ec37143720f09a4ca34e83ec2409893aa8cd79ace5b78a64276c

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "stegasoo"
-version = "4.1.2"
+version = "4.1.5"
 description = "Secure steganography with hybrid photo + passphrase + PIN authentication"
 readme = "README.md"
 license = "MIT"

rpi/BUILD_IMAGE.md

@@ -47,7 +47,7 @@ git clone -b 4.1 https://github.com/adlee-was-taken/stegasoo.git stegasoo
 
 ```bash
 # On your host machine:
-scp rpi/stegasoo-pi-arm64.tar.zst admin@stegasoo.local:/opt/stegasoo/rpi/
+scp rpi/stegasoo-rpi-runtime-env-arm64.tar.zst admin@stegasoo.local:/opt/stegasoo/rpi/
 ```
 
 This tarball contains:
@@ -98,7 +98,7 @@ This removes:
 
 The script validates all cleanup steps before finishing.
 
-## Step 9: Copy the Image
+## Step 9: Pull the Image
 
 Remove SD card, insert into your Linux machine:
 
@@ -106,23 +106,13 @@ Remove SD card, insert into your Linux machine:
 # Find the SD card device (CAREFUL!)
 lsblk
 
-# Copy (replace sdX with actual device, e.g., sda)
+# Pull image (auto-resizes to 16GB, compresses with zstd)
-sudo dd if=/dev/sdX of=stegasoo-rpi-$(date +%Y%m%d).img bs=4M status=progress
+sudo ./rpi/pull-image.sh /dev/sdX stegasoo-rpi-4.1.5.img.zst
 ```
 
-## Step 10: Shrink & Compress
+The script automatically resizes rootfs to 16GB, disables auto-expand, and compresses.
 
-```bash
+## Step 10: Distribute
-# Optional: Shrink image (saves space)
-wget https://raw.githubusercontent.com/Drewsif/PiShrink/master/pishrink.sh
-chmod +x pishrink.sh
-sudo ./pishrink.sh stegasoo-rpi-*.img
-
-# Compress (zstd is faster than xz with similar ratio)
-zstd -19 -T0 stegasoo-rpi-*.img
-```
-
-## Step 11: Distribute
 
 Upload `.img.zst` to GitHub Releases.
 
@@ -159,17 +149,17 @@ tar -cf - venv/ | zstd -19 -T0 > ~/stegasoo-venv.tar.zst
 
 # Create combined tarball (pyenv + venv pointer)
 cd ~
-tar -cf - .pyenv stegasoo-venv.tar.zst | zstd -19 -T0 > /tmp/stegasoo-pi-arm64.tar.zst
+tar -cf - .pyenv stegasoo-venv.tar.zst | zstd -19 -T0 > /tmp/stegasoo-rpi-runtime-env-arm64.tar.zst
 
 # Check size (should be ~50-60MB)
-ls -lh /tmp/stegasoo-pi-arm64.tar.zst
+ls -lh /tmp/stegasoo-rpi-runtime-env-arm64.tar.zst
 ```
 
 Pull to host and upload to GitHub releases:
 ```bash
 # On host:
-scp admin@stegasoo.local:/tmp/stegasoo-pi-arm64.tar.zst ./
+scp admin@stegasoo.local:/tmp/stegasoo-rpi-runtime-env-arm64.tar.zst ./
-# Upload to GitHub releases as stegasoo-pi-arm64.tar.zst
+# Upload to GitHub releases as stegasoo-rpi-runtime-env-arm64.tar.zst
 ```
 
 ---
@@ -183,7 +173,7 @@ sudo apt-get update && sudo apt-get install -y git zstd jq
 cd /opt && git clone -b 4.1 https://github.com/adlee-was-taken/stegasoo.git stegasoo
 
 # On host (copy tarball):
-scp rpi/stegasoo-pi-arm64.tar.zst admin@stegasoo.local:/opt/stegasoo/rpi/
+scp rpi/stegasoo-rpi-runtime-env-arm64.tar.zst admin@stegasoo.local:/opt/stegasoo/rpi/
 
 # On Pi (run setup):
 cd /opt/stegasoo && ./rpi/setup.sh
@@ -191,7 +181,6 @@ sudo systemctl start stegasoo
 curl -k https://localhost:5000
 sudo /opt/stegasoo/rpi/sanitize-for-image.sh
 
-# On host (pull image):
+# On host (pull image - auto-resizes to 16GB):
-sudo dd if=/dev/sdX of=stegasoo-rpi-$(date +%Y%m%d).img bs=4M status=progress
+sudo ./rpi/pull-image.sh /dev/sdX stegasoo-rpi-4.1.5.img.zst
-zstd -19 -T0 stegasoo-rpi-*.img
 ```

rpi/README.md

@@ -32,7 +32,7 @@ cd stegasoo
 - Raspberry Pi 4 or 5
 - Raspberry Pi OS Lite (64-bit) - Bookworm or later
 - 4GB+ RAM recommended (2GB minimum)
-- ~2GB free disk space
+- 16GB+ SD card (pre-built images are 16GB)
 - Internet connection
 
 ### Performance
@@ -49,6 +49,25 @@ If using a pre-built image from GitHub Releases:
 
 > **Security note**: Change the default password after setup with `passwd`
 
+## Updating an Existing Installation
+
+To update to the latest version:
+
+```bash
+cd /opt/stegasoo
+git pull origin main
+sudo systemctl restart stegasoo
+```
+
+That's it - the editable install means Python uses the source directly.
+
+**If dependencies changed** (check release notes), also run:
+```bash
+source venv/bin/activate
+pip install -e ".[web]"
+sudo systemctl restart stegasoo
+```
+
 ## After Installation
 
 ### Start the Service
@@ -180,18 +199,15 @@ After Pi shuts down, remove SD card and on another Linux machine:
 # Find SD card device (BE CAREFUL - wrong device = data loss!)
 lsblk
 
-# Copy (replace sdX with your SD card)
+# Pull image (auto-resizes to 16GB, compresses with zstd)
-sudo dd if=/dev/sdX of=stegasoo-rpi-$(date +%Y%m%d).img bs=4M status=progress
+sudo ./rpi/pull-image.sh /dev/sdX stegasoo-rpi-4.1.5.img.zst
-
-# Shrink the image (optional but recommended)
-wget https://raw.githubusercontent.com/Drewsif/PiShrink/master/pishrink.sh
-chmod +x pishrink.sh
-sudo ./pishrink.sh stegasoo-rpi-*.img
-
-# Compress (zstd is faster than xz with similar compression)
-zstd -19 -T0 stegasoo-rpi-*.img
 ```
 
+The `pull-image.sh` script automatically:
+- Resizes rootfs to exactly 16GB (consistent image size)
+- Disables Pi OS auto-expand
+- Compresses with zstd for fast decompression
+
 ### 6. Distribute
 
 Upload the `.img.zst` file to GitHub Releases.

rpi/banner.sh

@@ -0,0 +1,63 @@
+#!/bin/bash
+# Stegasoo Banner/Header Template
+# Source this file to use the banner functions
+#
+# Usage:
+#   source "$(dirname "${BASH_SOURCE[0]}")/banner.sh"
+#   print_banner "Raspberry Pi Setup"
+#   print_gradient_line
+
+# Colors
+STEGASOO_GOLD='\033[38;5;220m'
+STEGASOO_GRAY='\033[0;90m'
+STEGASOO_WHITE='\033[1;37m'
+STEGASOO_GREEN='\033[0;32m'
+STEGASOO_NC='\033[0m'
+
+# Gradient line (purple -> blue)
+print_gradient_line() {
+    echo -e "\033[38;5;93m══════════════\033[38;5;99m══════════════\033[38;5;105m══════════════\033[38;5;117m══════════════\033[0m"
+}
+
+# Starfield decoration line
+print_starfield() {
+    echo -e "${STEGASOO_GRAY} · .  · .  *  · .  *  · .  *  · .  *  · .  *  · .  ·${STEGASOO_NC}"
+}
+
+# ASCII logo (gold)
+print_logo() {
+    echo -e "${STEGASOO_GOLD}    ___  _____  ___    ___    _    ___    ___    ___${STEGASOO_NC}"
+    echo -e "${STEGASOO_GOLD}   / __||_   _|| __|  / __|  /_\\  / __|  / _ \\  / _ \\\\${STEGASOO_NC}"
+    echo -e "${STEGASOO_GOLD}   \\__ \\  | |  | _|  | (_ | / _ \\ \\__ \\ | (_) || (_) |${STEGASOO_NC}"
+    echo -e "${STEGASOO_GOLD}   |___/  |_|  |___|  \\___//_/ \\_\\|___/  \\___/  \\___/${STEGASOO_NC}"
+}
+
+# Full banner with optional subtitle
+# Usage: print_banner "Subtitle Text"
+print_banner() {
+    local subtitle="$1"
+    echo ""
+    print_gradient_line
+    print_starfield
+    print_logo
+    print_starfield
+    print_gradient_line
+    if [ -n "$subtitle" ]; then
+        echo -e "${STEGASOO_WHITE}                    ${subtitle}${STEGASOO_NC}"
+        print_gradient_line
+    fi
+}
+
+# Completion banner (green title)
+# Usage: print_complete_banner "Setup Complete!"
+print_complete_banner() {
+    local title="$1"
+    echo ""
+    print_gradient_line
+    print_starfield
+    print_logo
+    print_starfield
+    print_gradient_line
+    echo -e "\033[1;32m                      ${title}\033[0m"
+    print_gradient_line
+}

rpi/first-boot-wizard.sh

@@ -14,6 +14,10 @@
 INSTALL_DIR="/opt/stegasoo"
 FLAG_FILE="/etc/stegasoo-first-boot"
 PROFILE_HOOK="/etc/profile.d/stegasoo-wizard.sh"
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+
+# Source banner functions
+source "$SCRIPT_DIR/banner.sh"
 
 # Check if this is first boot
 if [ ! -f "$FLAG_FILE" ]; then
@@ -39,21 +43,12 @@ clear
 # Welcome
 # =============================================================================
 
+print_banner "First Boot Wizard"
 echo ""
-echo -e "\033[38;5;93m══════════════\033[38;5;99m══════════════\033[38;5;105m══════════════\033[38;5;117m══════════════\033[0m"
+gum style --foreground 245 "This wizard will help you configure your Stegasoo server"
-echo -e "\033[0;90m · .  · .  *  · .  *  · .  *  · .  *  · .  *  · .  ·\033[0m"
-echo -e "\033[38;5;220m    ___  _____  ___    ___    _    ___    ___    ___\033[0m"
-echo -e "\033[38;5;220m   / __||_   _|| __|  / __|  /_\\  / __|  / _ \\  / _ \\\\\033[0m"
-echo -e "\033[38;5;220m   \\__ \\  | |  | _|  | (_ | / _ \\ \\__ \\ | (_) || (_) |\033[0m"
-echo -e "\033[38;5;220m   |___/  |_|  |___|  \\___//_/ \\_\\|___/  \\___/  \\___/\033[0m"
-echo -e "\033[0;90m · .  · .  *  · .  *  · .  *  · .  *  · .  *  · .  ·\033[0m"
-echo -e "\033[38;5;93m══════════════\033[38;5;99m══════════════\033[38;5;105m══════════════\033[38;5;117m══════════════\033[0m"
-echo -e "\033[1;37m                    First Boot Wizard\033[0m"
-echo -e "\033[38;5;93m══════════════\033[38;5;99m══════════════\033[38;5;105m══════════════\033[38;5;117m══════════════\033[0m"
-
 echo ""
-gum style --foreground 245 "This wizard will help you configure your Stegasoo server."
+gum style --foreground 245 "You can reconfigure later by editing:"
-gum style --foreground 245 "You can reconfigure later by editing /etc/systemd/system/stegasoo.service"
+gum style --foreground 214 "  /etc/systemd/system/stegasoo.service"
 echo ""
 
 gum confirm "Ready to begin setup?" || exit 0
@@ -407,22 +402,11 @@ else
 fi
 
 echo ""
-echo ""
+print_complete_banner "Setup Complete!"
-echo -e "\033[38;5;93m══════════════\033[38;5;99m══════════════\033[38;5;105m══════════════\033[38;5;117m══════════════\033[0m"
-echo -e "\033[0;90m · .  · .  *  · .  *  · .  *  · .  *  · .  *  · .  ·\033[0m"
-echo -e "\033[38;5;220m    ___  _____  ___    ___    _    ___    ___    ___\033[0m"
-echo -e "\033[38;5;220m   / __||_   _|| __|  / __|  /_\\  / __|  / _ \\  / _ \\\\\033[0m"
-echo -e "\033[38;5;220m   \\__ \\  | |  | _|  | (_ | / _ \\ \\__ \\ | (_) || (_) |\033[0m"
-echo -e "\033[38;5;220m   |___/  |_|  |___|  \\___//_/ \\_\\|___/  \\___/  \\___/\033[0m"
-echo -e "\033[0;90m · .  · .  *  · .  *  · .  *  · .  *  · .  *  · .  ·\033[0m"
-echo -e "\033[38;5;93m══════════════\033[38;5;99m══════════════\033[38;5;105m══════════════\033[38;5;117m══════════════\033[0m"
-echo -e "\033[1;32m                      Setup Complete!\033[0m"
-echo -e "\033[38;5;93m══════════════\033[38;5;99m══════════════\033[38;5;105m══════════════\033[38;5;117m══════════════\033[0m"
-
 echo ""
 gum style --foreground 82 --bold "Create your admin account:"
-gum style --foreground 226 "  $ACCESS_URL"
+gum style --foreground 226 "  $ACCESS_URL_LOCAL"
-gum style --foreground 245 "  $ACCESS_URL_LOCAL (if mDNS works)"
+gum style --foreground 245 "  $ACCESS_URL (fallback IP)"
 
 if [ -n "$CHANNEL_KEY" ]; then
   echo ""

rpi/flash-stock-img.sh

@@ -120,28 +120,64 @@ read -p "Resize rootfs to 16GB for faster imaging? [Y/n] " resize_confirm
 if [[ ! "$resize_confirm" =~ ^[Nn]$ ]]; then
     echo "Resizing rootfs partition to 16GB..."
 
-    # Get boot partition end
+    # Get current partition size in bytes
+    CURRENT_SIZE=$(sudo blockdev --getsize64 "$ROOT_PART")
+    TARGET_BYTES=$((16 * 1024 * 1024 * 1024))  # 16GB in bytes
+
+    # Get boot partition end in sectors
     BOOT_END=$(sudo parted -s "$DEVICE" unit s print | grep "^ 1" | awk '{print $3}' | tr -d 's')
 
     # Calculate 16GB in sectors (512 byte sectors)
-    # 16GB = 16 * 1024 * 1024 * 1024 / 512 = 33554432 sectors
     ROOT_SIZE_SECTORS=33554432
     ROOT_END=$((BOOT_END + ROOT_SIZE_SECTORS))
 
-    # Delete and recreate partition 2 with fixed size
+    if [ "$CURRENT_SIZE" -lt "$TARGET_BYTES" ]; then
+        # EXPANDING: partition first, then filesystem
+        echo "Current partition is smaller than 16GB - expanding..."
+
+        # Delete and recreate partition 2 with 16GB size
+        echo "Expanding partition to 16GB..."
         sudo parted -s "$DEVICE" rm 2
         sudo parted -s "$DEVICE" mkpart primary ext4 $((BOOT_END + 1))s ${ROOT_END}s
 
         # Refresh partition table
         sudo partprobe "$DEVICE"
-    sleep 1
+        sleep 2
 
-    # Check and resize filesystem
+        # Expand filesystem to fill the new partition
+        echo "Expanding filesystem to fill partition..."
+        sudo e2fsck -f -y "$ROOT_PART" 2>/dev/null || true
+        sudo resize2fs "$ROOT_PART"
+    else
+        # SHRINKING: filesystem first, then partition
+        echo "Current partition is larger than 16GB - shrinking..."
+
+        # Check and shrink filesystem first
         echo "Checking filesystem..."
         sudo e2fsck -f -y "$ROOT_PART" 2>/dev/null || true
 
-    echo "Resizing filesystem to fit partition..."
+        # Shrink filesystem to 15.5GB (leave room for partition overhead)
+        echo "Shrinking filesystem to 15500M..."
+        sudo resize2fs "$ROOT_PART" 15500M
+
+        # Delete and recreate partition 2 with 16GB size
+        echo "Shrinking partition to 16GB..."
+        sudo parted -s "$DEVICE" rm 2
+        sudo parted -s "$DEVICE" mkpart primary ext4 $((BOOT_END + 1))s ${ROOT_END}s
+
+        # Refresh partition table
+        sudo partprobe "$DEVICE"
+        sleep 2
+
+        # Expand filesystem to fill the partition exactly
+        echo "Expanding filesystem to fill partition..."
+        sudo e2fsck -f -y "$ROOT_PART" 2>/dev/null || true
         sudo resize2fs "$ROOT_PART"
+    fi
+
+    # Verify and show result
+    echo "Verifying partition size..."
+    sudo parted -s "$DEVICE" unit GB print | grep "^ 2"
 
     # Disable Pi OS auto-expand on first boot
     echo "Disabling auto-expand..."
@@ -155,12 +191,10 @@ if [[ ! "$resize_confirm" =~ ^[Nn]$ ]]; then
     # Disable the systemd resize service
     sudo rm -f "$TEMP_ROOT/etc/systemd/system/multi-user.target.wants/rpi-resizerootfs.service"
 
-    # Remove init= parameter from cmdline.txt on boot partition (handled later)
-
     sudo umount "$TEMP_ROOT"
     rmdir "$TEMP_ROOT"
 
-    echo "  Rootfs resized to 16GB (auto-expand disabled)"
+    echo "  Rootfs set to 16GB (auto-expand disabled)"
 fi
 
 MOUNT_DIR=$(mktemp -d)
@@ -282,4 +316,17 @@ echo "  User: $PI_USER"
 echo "  SSH: enabled"
 echo "  WiFi: $WIFI_SSID"
 echo
-echo "Insert into Pi and boot. Find it with: ping $PI_HOSTNAME.local"
+echo "Insert into Pi and boot. Access via:"
+echo "  mDNS:  http://$PI_HOSTNAME.local"
+echo "  Find IP: ping $PI_HOSTNAME.local"
+echo
+echo "Once booted, SSH with: ssh $PI_USER@$PI_HOSTNAME.local"
+
+# If we resized, remind about pull-image.sh
+if [[ ! "$resize_confirm" =~ ^[Nn]$ ]]; then
+    echo
+    echo "=== After setup, use pull-image.sh to create distributable image ==="
+    echo "  ./pull-image.sh $DEVICE stegasoo-rpi-VERSION.img.zst"
+    echo
+    echo "This will only pull the 16GB partition, not the entire SD card."
+fi

rpi/host-requirements.txt

@@ -0,0 +1,29 @@
+# Host Machine Dependencies for Stegasoo Pi Scripts
+# =================================================
+#
+# Quick install (Debian/Ubuntu):
+#   sudo apt install parted e2fsprogs zstd zip bc pv jq unzip sshpass
+#
+# Or install with this file:
+#   sudo apt install $(grep -v '^#' rpi/host-requirements.txt | grep -v '^$' | xargs)
+
+# pull-image.sh - Create distributable images
+parted              # Partition table reading/writing
+e2fsprogs           # e2fsck, resize2fs for ext4
+zstd                # Compression (zstd -T0 -3)
+zip                 # Optional .zst.zip wrapper for GitHub
+bc                  # Floating point math for size display
+pv                  # Progress bar (optional, falls back to dd status)
+
+# flash-image.sh - Flash images to SD cards
+unzip               # Extract .zst.zip wrappers
+zstd                # Decompress .zst images
+pv                  # Progress bar (optional)
+jq                  # Parse config.json for headless WiFi (optional)
+
+# kickoff-pi-test.sh - Automated flash+test
+sshpass             # Non-interactive SSH with password
+avahi-utils         # avahi-resolve for .local hostname lookup
+
+# Optional tools
+rpi-imager          # Faster flashing (flash-image.sh falls back to dd)

rpi/kickoff-pi-test.sh

@@ -0,0 +1,193 @@
+#!/bin/bash
+#
+# Stegasoo Pi Test Kickoff Script
+# Automates: flash -> wait for boot -> setup -> test
+#
+# Usage: ./kickoff-pi-test.sh <image.img.zst> </dev/sdX>
+#
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+
+# Pi connection settings
+PI_HOST="stegasoo.local"
+PI_USER="admin"
+PI_PASS="stegasoo"
+
+# Colors
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+CYAN='\033[0;36m'
+NC='\033[0m'
+
+# -----------------------------------------------------------------------------
+# Helper functions
+# -----------------------------------------------------------------------------
+
+# Wait for Pi to be reachable
+wait_for_pi() {
+    local attempt=1
+    ssh-keygen -R "$PI_HOST" 2>/dev/null
+
+    echo "Waiting for $PI_USER@$PI_HOST..."
+    while ! sshpass -p "$PI_PASS" ssh -o ConnectTimeout=2 -o StrictHostKeyChecking=no -o BatchMode=no -o UserKnownHostsFile=/dev/null "$PI_USER@$PI_HOST" "exit" 2>/dev/null; do
+        printf "\rAttempt %d..." "$attempt"
+        ((attempt++))
+        sleep 2
+    done
+
+    printf "\r${GREEN}✓ Ready after %d attempts${NC}\n" "$attempt"
+    printf '\a'  # Terminal bell
+}
+
+# Run command on Pi (non-interactive)
+run_on_pi() {
+    sshpass -p "$PI_PASS" ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null "$PI_USER@$PI_HOST" "$@"
+}
+
+# Run command on Pi (interactive/PTY)
+run_on_pi_interactive() {
+    sshpass -p "$PI_PASS" ssh -t -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null "$PI_USER@$PI_HOST" "$@"
+}
+
+# Copy file to Pi
+scp_to_pi() {
+    local src="$1"
+    local dst="$2"
+    sshpass -p "$PI_PASS" scp -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null "$src" "$PI_USER@$PI_HOST:$dst"
+}
+
+# Interactive SSH session
+ssh_pi() {
+    ssh-keygen -R "$PI_HOST" 2>/dev/null
+    sshpass -p "$PI_PASS" ssh -t -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null "$PI_USER@$PI_HOST" "$@"
+}
+
+# -----------------------------------------------------------------------------
+# Main
+# -----------------------------------------------------------------------------
+
+if [[ $# -lt 2 ]]; then
+    echo "Usage: $0 <image.img.zst> </dev/sdX>"
+    echo ""
+    echo "Example: $0 stegasoo-v4.1.img.zst /dev/sda"
+    exit 1
+fi
+
+IMAGE="$1"
+DEVICE="$2"
+
+if [[ ! -f "$IMAGE" ]]; then
+    echo -e "${RED}Error: Image file not found: $IMAGE${NC}"
+    exit 1
+fi
+
+if [[ ! -b "$DEVICE" ]]; then
+    echo -e "${RED}Error: Device not found: $DEVICE${NC}"
+    exit 1
+fi
+
+echo -e "${CYAN}╔═══════════════════════════════════════════════════════════════╗${NC}"
+echo -e "${CYAN}║              Stegasoo Pi Test Kickoff                         ║${NC}"
+echo -e "${CYAN}╚═══════════════════════════════════════════════════════════════╝${NC}"
+echo ""
+echo -e "Image:  ${YELLOW}$IMAGE${NC}"
+echo -e "Device: ${YELLOW}$DEVICE${NC}"
+echo ""
+
+# -----------------------------------------------------------------------------
+# Step 1: Flash the image
+# -----------------------------------------------------------------------------
+echo -e "${GREEN}[1/8]${NC} Flashing image..."
+echo ""
+
+# Auto-answer: "yes" for confirm, "y" for wipe, "y" for resize
+printf 'yes\ny\ny\n' | "$SCRIPT_DIR/flash-stock-img.sh" "$IMAGE" "$DEVICE"
+
+echo ""
+echo -e "${GREEN}[2/8]${NC} Flash complete! Waiting for SD card insertion..."
+echo ""
+
+# -----------------------------------------------------------------------------
+# Step 2: Wait for user to insert SD card
+# -----------------------------------------------------------------------------
+echo -e "${YELLOW}════════════════════════════════════════════════════════════════${NC}"
+echo -e "${YELLOW}  Insert SD card into Pi and power on${NC}"
+echo -e "${YELLOW}════════════════════════════════════════════════════════════════${NC}"
+echo ""
+read -p "Press ENTER when Pi is booting..."
+
+echo ""
+
+# -----------------------------------------------------------------------------
+# Step 3: Wait for Pi to be ready
+# -----------------------------------------------------------------------------
+echo -e "${GREEN}[3/8]${NC} Waiting for Pi to boot..."
+echo ""
+
+wait_for_pi
+
+# -----------------------------------------------------------------------------
+# Step 4: Pre-setup (install dependencies)
+# -----------------------------------------------------------------------------
+echo ""
+echo -e "${GREEN}[4/8]${NC} Installing dependencies on Pi..."
+echo ""
+
+run_on_pi "sudo chown admin:admin /opt && sudo apt-get update && sudo apt-get install -y git zstd jq"
+
+# -----------------------------------------------------------------------------
+# Step 5: Clone repo
+# -----------------------------------------------------------------------------
+echo ""
+echo -e "${GREEN}[5/8]${NC} Cloning Stegasoo repo..."
+echo ""
+
+run_on_pi "cd /opt && git clone -b 4.1 https://github.com/adlee-was-taken/stegasoo.git stegasoo"
+
+# -----------------------------------------------------------------------------
+# Step 6: Copy pre-built tarball
+# -----------------------------------------------------------------------------
+echo ""
+echo -e "${GREEN}[6/8]${NC} Copying pre-built tarball to Pi..."
+echo ""
+
+TARBALL="$SCRIPT_DIR/stegasoo-rpi-runtime-env-arm64.tar.zst"
+if [[ -f "$TARBALL" ]]; then
+    scp_to_pi "$TARBALL" "/opt/stegasoo/rpi/"
+    echo -e "  ${GREEN}✓${NC} Tarball copied"
+else
+    echo -e "  ${YELLOW}⚠${NC} Tarball not found at $TARBALL"
+    echo -e "  ${YELLOW}⚠${NC} Setup will build from source (takes longer)"
+fi
+
+# -----------------------------------------------------------------------------
+# Step 7: Run setup
+# -----------------------------------------------------------------------------
+echo ""
+echo -e "${GREEN}[7/8]${NC} Running setup.sh on Pi..."
+echo ""
+
+run_on_pi_interactive "cd /opt/stegasoo && ./rpi/setup.sh"
+
+# -----------------------------------------------------------------------------
+# Step 8: Test it works
+# -----------------------------------------------------------------------------
+echo ""
+echo -e "${GREEN}[8/8]${NC} Testing Stegasoo..."
+echo ""
+
+run_on_pi "sudo systemctl start stegasoo && sleep 2 && curl -sk https://localhost:5000 | head -5"
+
+echo ""
+echo -e "${GREEN}════════════════════════════════════════════════════════════════${NC}"
+echo -e "${GREEN}  Build complete! Pi is ready for testing.${NC}"
+echo -e "${GREEN}════════════════════════════════════════════════════════════════${NC}"
+echo ""
+echo -e "Access: ${YELLOW}https://stegasoo.local:5000${NC}"
+echo ""
+read -p "Press ENTER to SSH into Pi for manual testing..."
+
+ssh_pi

rpi/pull-image.sh

@@ -1,31 +1,26 @@
 #!/bin/bash
+# Pull Raspberry Pi image from SD card (after setup)
+# Resizes rootfs to 16GB for consistent image size, then pulls
 #
-# Pull Stegasoo image from SD card
+# Usage: ./pull-image.sh <device> <output.img.zst>
-# Auto-detects SD card, copies with progress, shrinks, and compresses
+# Example: ./pull-image.sh /dev/sdb stegasoo-rpi-4.1.5.img.zst
-#
-# Usage: ./pull-image.sh [output-name] [device]
-#        Output will be: stegasoo-rpi-YYYYMMDD.img.zst (or custom name)
-#        Use .img extension to skip compression: ./pull-image.sh foo.img
-#
-# If device is specified, skips auto-detection (useful for large drives)
-#
 
 set -e
 
 RED='\033[0;31m'
 GREEN='\033[0;32m'
 YELLOW='\033[1;33m'
-BLUE='\033[0;34m'
 BOLD='\033[1m'
 NC='\033[0m'
 
-# Check for required tools
+if [ $# -ne 2 ]; then
-for cmd in dd pv zstd lsblk; do
+    echo "Usage: $0 <device> <output.img.zst>"
-    if ! command -v $cmd &> /dev/null; then
+    echo "Example: $0 /dev/sdb stegasoo-rpi-4.1.5.img.zst"
-        echo -e "${RED}Error: $cmd is required but not installed.${NC}"
     exit 1
-    fi
+fi
-done
+
+DEVICE="$1"
+OUTPUT="$2"
 
 # Check for root
 if [ "$EUID" -ne 0 ]; then
@@ -33,204 +28,185 @@ if [ "$EUID" -ne 0 ]; then
     exit 1
 fi
 
-# Output filename and optional device
+if [ ! -b "$DEVICE" ]; then
-if [ -n "$1" ]; then
+    echo -e "${RED}Error: Device not found: $DEVICE${NC}"
-    OUTPUT="$1"
+    exit 1
-else
-    OUTPUT="stegasoo-rpi-$(date +%Y%m%d).img.zst"
-fi
-MANUAL_DEVICE="$2"
-
-# Check if output ends in .img (skip compression) or .zst (compress)
-SKIP_COMPRESS=false
-if [[ "$OUTPUT" == *.img ]]; then
-    IMG_FILE="$OUTPUT"
-    SKIP_COMPRESS=true
-elif [[ "$OUTPUT" == *.zst ]]; then
-    IMG_FILE="${OUTPUT%.zst}"
-else
-    # No recognized extension, add .img.zst
-    IMG_FILE="${OUTPUT}.img"
-    OUTPUT="${OUTPUT}.img.zst"
 fi
 
-echo -e "${BLUE}"
+echo -e "${BOLD}Device info:${NC}"
-echo "╔═══════════════════════════════════════════════════════════════╗"
+lsblk "$DEVICE"
-echo "║              Stegasoo SD Card Image Puller                    ║"
-echo "╚═══════════════════════════════════════════════════════════════╝"
-echo -e "${NC}"
-
-# Use manual device or auto-detect
-if [ -n "$MANUAL_DEVICE" ]; then
-    # Manual device specified
-    if [ ! -b "$MANUAL_DEVICE" ]; then
-        echo -e "${RED}Error: $MANUAL_DEVICE is not a block device${NC}"
-        exit 1
-    fi
-    SELECTED="$MANUAL_DEVICE"
-    echo -e "Using specified device: ${YELLOW}$SELECTED${NC}"
-    echo ""
-    lsblk "$SELECTED" -o NAME,SIZE,TYPE,MODEL
-    echo ""
-else
-    # Auto-detect SD card candidates
-    # Looking for: USB/removable, 8-128GB, not mounted as root filesystem
-    echo -e "${BOLD}Scanning for SD cards...${NC}"
-    echo ""
-
-    declare -a CANDIDATES
-    declare -a CANDIDATE_INFO
-
-    while IFS= read -r line; do
-        DEV=$(echo "$line" | awk '{print $1}')
-        SIZE=$(echo "$line" | awk '{print $2}')
-        TYPE=$(echo "$line" | awk '{print $3}')
-        TRAN=$(echo "$line" | awk '{print $4}')
-        MODEL=$(echo "$line" | awk '{print $5" "$6" "$7}' | xargs)
-
-        # Skip if it's the root filesystem
-        if mount | grep -q "^/dev/${DEV}[0-9]* on / "; then
-            continue
-        fi
-
-        # Skip if any partition is mounted as root
-        ROOT_DEV=$(mount | grep " on / " | awk '{print $1}' | sed 's/[0-9]*$//')
-        if [[ "/dev/$DEV" == "$ROOT_DEV" ]]; then
-            continue
-        fi
-
-        # Get size in bytes for reliable comparison
-        SIZE_BYTES=$(lsblk -b -d -o SIZE -n "/dev/$DEV" 2>/dev/null | tr -d ' ')
-        SIZE_GB_INT=$((SIZE_BYTES / 1073741824))  # 1024^3
-
-        # Check if size is in SD card range (8GB - 128GB)
-        if [ "$SIZE_GB_INT" -ge 8 ] && [ "$SIZE_GB_INT" -le 128 ]; then
-            CANDIDATES+=("/dev/$DEV")
-            CANDIDATE_INFO+=("$SIZE $TYPE ${TRAN:-???} $MODEL")
-        fi
-    done < <(lsblk -d -o NAME,SIZE,TYPE,TRAN,MODEL -n | grep "disk")
-
-    if [ ${#CANDIDATES[@]} -eq 0 ]; then
-        echo -e "${RED}No SD card candidates found.${NC}"
-        echo "Looking for USB/removable disks between 8GB and 128GB."
-        echo ""
-        echo "Available disks:"
-        lsblk -d -o NAME,SIZE,TYPE,TRAN,MODEL
-        echo ""
-        echo -e "${YELLOW}Tip: Specify device manually: $0 output.img.zst /dev/sdX${NC}"
-        exit 1
-    fi
-
-    echo -e "${GREEN}Found ${#CANDIDATES[@]} candidate(s):${NC}"
-    echo ""
-
-    for i in "${!CANDIDATES[@]}"; do
-        echo -e "  ${BOLD}[$((i+1))]${NC} ${CANDIDATES[$i]} - ${CANDIDATE_INFO[$i]}"
-    done
-
-    echo ""
-
-    if [ ${#CANDIDATES[@]} -eq 1 ]; then
-        SELECTED="${CANDIDATES[0]}"
-        echo -e "Auto-selected: ${YELLOW}$SELECTED${NC}"
-    else
-        read -p "Select device [1-${#CANDIDATES[@]}]: " -r
-        if [[ ! $REPLY =~ ^[0-9]+$ ]] || [ "$REPLY" -lt 1 ] || [ "$REPLY" -gt ${#CANDIDATES[@]} ]; then
-            echo -e "${RED}Invalid selection.${NC}"
-            exit 1
-        fi
-        SELECTED="${CANDIDATES[$((REPLY-1))]}"
-    fi
-fi
-
-# Show partitions
-echo ""
-echo -e "${BOLD}Partitions on $SELECTED:${NC}"
-lsblk "$SELECTED" -o NAME,SIZE,FSTYPE,LABEL,MOUNTPOINT
-echo ""
-
-# Final confirmation
-echo -e "${RED}╔═══════════════════════════════════════════════════════════════╗${NC}"
-echo -e "${RED}║  WARNING: This will read the ENTIRE device:                   ║${NC}"
-echo -e "${RED}║  $SELECTED                                                  ║${NC}"
-echo -e "${RED}╚═══════════════════════════════════════════════════════════════╝${NC}"
-echo ""
-echo -e "Output: ${YELLOW}$OUTPUT${NC}"
-echo ""
-read -p "Continue? [y/N] " -n 1 -r
 echo
-if [[ ! $REPLY =~ ^[Yy]$ ]]; then
+
+# Find partitions
+if [ -b "${DEVICE}1" ]; then
+    BOOT_PART="${DEVICE}1"
+    ROOT_PART="${DEVICE}2"
+elif [ -b "${DEVICE}p1" ]; then
+    BOOT_PART="${DEVICE}p1"
+    ROOT_PART="${DEVICE}p2"
+else
+    echo -e "${RED}Error: Could not find partitions${NC}"
+    exit 1
+fi
+
+# Unmount any mounted partitions
+echo -e "${YELLOW}Unmounting partitions...${NC}"
+umount "$BOOT_PART" 2>/dev/null || true
+umount "$ROOT_PART" 2>/dev/null || true
+
+# ============================================================================
+# Resize rootfs to 16GB
+# ============================================================================
+echo
+echo -e "${BOLD}Checking partition size...${NC}"
+
+# Get current partition size in bytes
+CURRENT_SIZE=$(blockdev --getsize64 "$ROOT_PART")
+TARGET_BYTES=$((16 * 1024 * 1024 * 1024))  # 16GB in bytes
+CURRENT_GB=$(echo "scale=2; $CURRENT_SIZE / 1073741824" | bc)
+
+echo "  Current rootfs size: ${CURRENT_GB}GB"
+
+if [ "$CURRENT_SIZE" -gt "$TARGET_BYTES" ]; then
+    echo -e "${YELLOW}Resizing rootfs to 16GB...${NC}"
+
+    # Get boot partition end in sectors
+    BOOT_END=$(parted -s "$DEVICE" unit s print | grep "^ 1" | awk '{print $3}' | tr -d 's')
+
+    # Calculate 16GB in sectors (512 byte sectors)
+    ROOT_SIZE_SECTORS=33554432
+    ROOT_END=$((BOOT_END + ROOT_SIZE_SECTORS))
+
+    # SHRINKING: filesystem first, then partition
+    echo "  Checking filesystem..."
+    e2fsck -f -y "$ROOT_PART" 2>/dev/null || true
+
+    # Shrink filesystem to 15.5GB (leave room for partition overhead)
+    echo "  Shrinking filesystem to 15500M..."
+    resize2fs "$ROOT_PART" 15500M
+
+    # Delete and recreate partition 2 with 16GB size
+    echo "  Shrinking partition to 16GB..."
+    parted -s "$DEVICE" rm 2
+    parted -s "$DEVICE" mkpart primary ext4 $((BOOT_END + 1))s ${ROOT_END}s
+
+    # Refresh partition table
+    partprobe "$DEVICE"
+    sleep 2
+
+    # Expand filesystem to fill the partition exactly
+    echo "  Expanding filesystem to fill partition..."
+    e2fsck -f -y "$ROOT_PART" 2>/dev/null || true
+    resize2fs "$ROOT_PART"
+
+    echo -e "${GREEN}  Rootfs resized to 16GB${NC}"
+elif [ "$CURRENT_SIZE" -lt "$TARGET_BYTES" ]; then
+    echo -e "${YELLOW}  Rootfs is smaller than 16GB - expanding...${NC}"
+
+    # Get boot partition end in sectors
+    BOOT_END=$(parted -s "$DEVICE" unit s print | grep "^ 1" | awk '{print $3}' | tr -d 's')
+    ROOT_SIZE_SECTORS=33554432
+    ROOT_END=$((BOOT_END + ROOT_SIZE_SECTORS))
+
+    # EXPANDING: partition first, then filesystem
+    parted -s "$DEVICE" rm 2
+    parted -s "$DEVICE" mkpart primary ext4 $((BOOT_END + 1))s ${ROOT_END}s
+
+    partprobe "$DEVICE"
+    sleep 2
+
+    e2fsck -f -y "$ROOT_PART" 2>/dev/null || true
+    resize2fs "$ROOT_PART"
+
+    echo -e "${GREEN}  Rootfs expanded to 16GB${NC}"
+else
+    echo -e "${GREEN}  Rootfs already ~16GB${NC}"
+fi
+
+# ============================================================================
+# Disable auto-expand on first boot
+# ============================================================================
+echo
+echo -e "${YELLOW}Disabling auto-expand...${NC}"
+TEMP_ROOT=$(mktemp -d)
+mount "$ROOT_PART" "$TEMP_ROOT"
+
+# Remove resize2fs_once service if it exists
+rm -f "$TEMP_ROOT/etc/init.d/resize2fs_once"
+rm -f "$TEMP_ROOT/etc/rc3.d/S01resize2fs_once"
+
+# Disable the systemd resize service
+rm -f "$TEMP_ROOT/etc/systemd/system/multi-user.target.wants/rpi-resizerootfs.service"
+
+umount "$TEMP_ROOT"
+rmdir "$TEMP_ROOT"
+echo -e "${GREEN}  Auto-expand disabled${NC}"
+
+# ============================================================================
+# Pull image
+# ============================================================================
+echo
+echo -e "${BOLD}Partition table:${NC}"
+parted -s "$DEVICE" unit s print
+echo
+
+# Get the end of the last partition (partition 2 = rootfs)
+END_SECTOR=$(parted -s "$DEVICE" unit s print | grep "^ 2" | awk '{print $3}' | tr -d 's')
+
+if [ -z "$END_SECTOR" ]; then
+    echo -e "${RED}Error: Could not determine partition 2 end sector${NC}"
+    exit 1
+fi
+
+# Add a small buffer (1MB = 2048 sectors) for safety
+TOTAL_SECTORS=$((END_SECTOR + 2048))
+TOTAL_BYTES=$((TOTAL_SECTORS * 512))
+TOTAL_GB=$(echo "scale=2; $TOTAL_BYTES / 1073741824" | bc)
+
+echo -e "Image size: ${YELLOW}~${TOTAL_GB}GB${NC} (${TOTAL_SECTORS} sectors)"
+echo -e "Output: ${YELLOW}$OUTPUT${NC}"
+echo
+
+read -p "Proceed with image pull? [Y/n] " confirm
+if [[ "$confirm" =~ ^[Nn]$ ]]; then
     echo "Aborted."
     exit 1
 fi
 
-# Get device size for pv
+echo
-DEV_SIZE=$(blockdev --getsize64 "$SELECTED")
+echo -e "${GREEN}Pulling image...${NC}"
+echo
 
-echo ""
+# Use pv if available for progress, otherwise fallback to dd status
-echo -e "${GREEN}[1/4]${NC} Copying image from $SELECTED..."
+if command -v pv &> /dev/null; then
-dd if="$SELECTED" bs=4M status=none | pv -s "$DEV_SIZE" > "$IMG_FILE"
+    dd if="$DEVICE" bs=512 count=$TOTAL_SECTORS 2>/dev/null | \
-sync
+        pv -s $TOTAL_BYTES | \
-
+        zstd -T0 -3 > "$OUTPUT"
-echo ""
-echo -e "${GREEN}[2/4]${NC} Re-enabling auto-expand for distribution..."
-# Mount the image and restore auto-expand service (may have been disabled during build)
-LOOP_DEV=$(losetup -f --show -P "$IMG_FILE")
-if [ -n "$LOOP_DEV" ]; then
-    TEMP_MOUNT=$(mktemp -d)
-    if mount "${LOOP_DEV}p2" "$TEMP_MOUNT" 2>/dev/null; then
-        # Re-enable the resize service if the service file exists
-        SERVICE_FILE="$TEMP_MOUNT/lib/systemd/system/rpi-resizerootfs.service"
-        SERVICE_LINK="$TEMP_MOUNT/etc/systemd/system/multi-user.target.wants/rpi-resizerootfs.service"
-        if [ -f "$SERVICE_FILE" ] && [ ! -L "$SERVICE_LINK" ]; then
-            mkdir -p "$(dirname "$SERVICE_LINK")"
-            ln -sf /lib/systemd/system/rpi-resizerootfs.service "$SERVICE_LINK"
-            echo -e "  ${GREEN}✓${NC} Auto-expand service re-enabled"
-        elif [ -L "$SERVICE_LINK" ]; then
-            echo -e "  ${GREEN}✓${NC} Auto-expand already enabled"
-        else
-            echo -e "  ${YELLOW}⚠${NC} Could not find resize service file"
-        fi
-        umount "$TEMP_MOUNT"
-    else
-        echo -e "  ${YELLOW}⚠${NC} Could not mount rootfs, skipping auto-expand fix"
-    fi
-    rmdir "$TEMP_MOUNT" 2>/dev/null || true
-    losetup -d "$LOOP_DEV"
 else
-    echo -e "  ${YELLOW}⚠${NC} Could not create loop device, skipping auto-expand fix"
+    dd if="$DEVICE" bs=512 count=$TOTAL_SECTORS status=progress | \
+        zstd -T0 -3 > "$OUTPUT"
 fi
 
-echo ""
+echo
-echo -e "${GREEN}[3/4]${NC} Shrinking image..."
+echo -e "${GREEN}Done!${NC} Image saved to: $OUTPUT"
-if command -v pishrink.sh &> /dev/null; then
+ls -lh "$OUTPUT"
-    pishrink.sh "$IMG_FILE"
-elif [ -f "./pishrink.sh" ]; then
-    bash ./pishrink.sh "$IMG_FILE"
-elif [ -f "../pishrink.sh" ]; then
-    bash ../pishrink.sh "$IMG_FILE"
-else
-    echo -e "${YELLOW}pishrink.sh not found, skipping shrink step.${NC}"
-    echo "Download from: https://github.com/Drewsif/PiShrink"
-fi
 
-echo ""
+# ============================================================================
-if [ "$SKIP_COMPRESS" = true ]; then
+# Optional: Zip-wrap for GitHub releases
-    echo -e "${GREEN}[4/4]${NC} Skipping compression (.img output)"
+# ============================================================================
-    FINAL_SIZE=$(du -h "$IMG_FILE" | awk '{print $1}')
+echo
-    OUTPUT="$IMG_FILE"
+read -p "Create .zst.zip wrapper for GitHub? [y/N] " zip_confirm
+if [[ "$zip_confirm" =~ ^[Yy]$ ]]; then
+    ZIP_OUTPUT="${OUTPUT}.zip"
+    echo -e "${YELLOW}Creating zip wrapper (store mode, no compression)...${NC}"
+    zip -0 "$ZIP_OUTPUT" "$OUTPUT"
+    echo -e "${GREEN}Done!${NC} Upload this to GitHub Releases:"
+    ls -lh "$ZIP_OUTPUT"
+    echo
+    echo "Users can flash with:"
+    echo "  sudo ./rpi/flash-image.sh $ZIP_OUTPUT"
 else
-    echo -e "${GREEN}[4/4]${NC} Compressing with zstd..."
+    echo
-    pv "$IMG_FILE" | zstd -19 -T0 -q > "$OUTPUT"
+    echo "To verify:"
-    rm -f "$IMG_FILE"
+    echo "  zstdcat $OUTPUT | fdisk -l /dev/stdin"
-    FINAL_SIZE=$(du -h "$OUTPUT" | awk '{print $1}')
 fi
-
-echo ""
-echo -e "${GREEN}╔═══════════════════════════════════════════════════════════════╗${NC}"
-echo -e "${GREEN}║                    Image Complete!                            ║${NC}"
-echo -e "${GREEN}╚═══════════════════════════════════════════════════════════════╝${NC}"
-echo ""
-echo -e "Output: ${YELLOW}$OUTPUT${NC}"
-echo -e "Size:   ${YELLOW}$FINAL_SIZE${NC}"
-echo ""

rpi/sanitize-for-image.sh

@@ -29,6 +29,10 @@ GRAY='\033[0;90m'
 BOLD='\033[1m'
 NC='\033[0m'
 
+# Source banner functions
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+source "$SCRIPT_DIR/banner.sh"
+
 # Show help
 show_help() {
     echo "Stegasoo Sanitize Script - Prepare Pi for SD Card Imaging"
@@ -70,21 +74,11 @@ if [ "$EUID" -ne 0 ]; then
 fi
 
 clear
-echo ""
-echo -e "\033[38;5;93m══════════════\033[38;5;99m══════════════\033[38;5;105m══════════════\033[38;5;117m══════════════\033[0m"
-echo -e "${GRAY} · .  · .  *  · .  *  · .  *  · .  *  · .  *  · .  ·${NC}"
-echo -e "\033[38;5;220m    ___  _____  ___    ___    _    ___    ___    ___\033[0m"
-echo -e "\033[38;5;220m   / __||_   _|| __|  / __|  /_\\\\  / __|  / _ \\\\  / _ \\\\\033[0m"
-echo -e "\033[38;5;220m   \\\\__ \\\\  | |  | _|  | (_ | / _ \\\\ \\\\__ \\\\ | (_) || (_) |\033[0m"
-echo -e "\033[38;5;220m   |___/  |_|  |___|  \\___|/_/ \\_\\\\|___/  \\\\___/  \\\\___/\033[0m"
-echo -e "${GRAY} · .  · .  *  · .  *  · .  *  · .  *  · .  *  · .  ·${NC}"
-echo -e "\033[38;5;93m══════════════\033[38;5;99m══════════════\033[38;5;105m══════════════\033[38;5;117m══════════════\033[0m"
 if [ "$SOFT_RESET" = true ]; then
-    echo -e "\033[1;37m                  Soft Reset (Factory)\033[0m"
+    print_banner "Soft Reset (Factory)"
 else
-    echo -e "\033[1;37m                  Sanitize for Imaging\033[0m"
+    print_banner "Sanitize for Imaging"
 fi
-echo -e "\033[38;5;93m══════════════\033[38;5;99m══════════════\033[38;5;105m══════════════\033[38;5;117m══════════════\033[0m"
 echo ""
 
 if [ "$SOFT_RESET" = true ]; then

rpi/setup.sh

@@ -29,6 +29,33 @@ GRAY='\033[0;90m'
 BOLD='\033[1m'
 NC='\033[0m' # No Color
 
+# Source banner.sh if available (for local runs), otherwise define inline
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" 2>/dev/null && pwd)"
+if [ -f "$SCRIPT_DIR/banner.sh" ]; then
+    source "$SCRIPT_DIR/banner.sh"
+else
+    # Inline banner functions for curl-pipe execution
+    print_gradient_line() {
+        echo -e "\033[38;5;93m══════════════\033[38;5;99m══════════════\033[38;5;105m══════════════\033[38;5;117m══════════════\033[0m"
+    }
+    print_banner() {
+        local subtitle="$1"
+        echo ""
+        print_gradient_line
+        echo -e "\033[0;90m · .  · .  *  · .  *  · .  *  · .  *  · .  *  · .  ·\033[0m"
+        echo -e "\033[38;5;220m    ___  _____  ___    ___    _    ___    ___    ___\033[0m"
+        echo -e "\033[38;5;220m   / __||_   _|| __|  / __|  /_\\  / __|  / _ \\  / _ \\\\\033[0m"
+        echo -e "\033[38;5;220m   \\__ \\  | |  | _|  | (_ | / _ \\ \\__ \\ | (_) || (_) |\033[0m"
+        echo -e "\033[38;5;220m   |___/  |_|  |___|  \\___//_/ \\_\\|___/  \\___/  \\___/\033[0m"
+        echo -e "\033[0;90m · .  · .  *  · .  *  · .  *  · .  *  · .  *  · .  ·\033[0m"
+        print_gradient_line
+        if [ -n "$subtitle" ]; then
+            echo -e "\033[1;37m                    ${subtitle}\033[0m"
+            print_gradient_line
+        fi
+    }
+fi
+
 # Show help
 show_help() {
     echo "Stegasoo Raspberry Pi Setup Script"
@@ -82,17 +109,7 @@ for config_file in "/etc/stegasoo.conf" "$HOME/.config/stegasoo/stegasoo.conf";
 done
 
 clear
-echo ""
+print_banner "Raspberry Pi Setup"
-echo -e "\033[38;5;93m══════════════\033[38;5;99m══════════════\033[38;5;105m══════════════\033[38;5;117m══════════════\033[0m"
-echo -e "${GRAY} · .  · .  *  · .  *  · .  *  · .  *  · .  *  · .  ·${NC}"
-echo -e "\033[38;5;220m    ___  _____  ___    ___    _    ___    ___    ___\033[0m"
-echo -e "\033[38;5;220m   / __||_   _|| __|  / __|  /_\\\\  / __|  / _ \\\\  / _ \\\\\033[0m"
-echo -e "\033[38;5;220m   \\\\__ \\\\  | |  | _|  | (_ | / _ \\\\ \\\\__ \\\\ | (_) || (_) |\033[0m"
-echo -e "\033[38;5;220m   |___/  |_|  |___|  \\___|/_/ \\_\\\\|___/  \\\\___/  \\\\___/\033[0m"
-echo -e "${GRAY} · .  · .  *  · .  *  · .  *  · .  *  · .  *  · .  ·${NC}"
-echo -e "\033[38;5;93m══════════════\033[38;5;99m══════════════\033[38;5;105m══════════════\033[38;5;117m══════════════\033[0m"
-echo -e "\033[1;37m                   Raspberry Pi Setup\033[0m"
-echo -e "\033[38;5;93m══════════════\033[38;5;99m══════════════\033[38;5;105m══════════════\033[38;5;117m══════════════\033[0m"
 echo ""
 echo "  This will install Stegasoo with full DCT support"
 echo "  Estimated time: ~2 minutes (pre-built) or 15-20 min (from source)"
@@ -183,8 +200,8 @@ fi
 
 # Pre-built environment tarball (skips 20+ min compile time)
 # Includes both pyenv Python 3.12 AND venv with all dependencies
-PREBUILT_TARBALL="$INSTALL_DIR/rpi/stegasoo-pi-arm64.tar.zst"
+PREBUILT_TARBALL="$INSTALL_DIR/rpi/stegasoo-rpi-runtime-env-arm64.tar.zst"
-PREBUILT_URL="${PREBUILT_URL:-https://github.com/adlee-was-taken/stegasoo/releases/download/v4.1.3/stegasoo-pi-arm64.tar.zst}"
+PREBUILT_URL="${PREBUILT_URL:-https://github.com/adlee-was-taken/stegasoo/releases/download/v4.1.5/stegasoo-rpi-runtime-env-arm64.tar.zst}"
 USE_PREBUILT=true
 
 # Use local tarball if present, otherwise will download
@@ -424,19 +441,35 @@ if systemctl is-active --quiet stegasoo 2>/dev/null; then
     echo -e "\033[38;5;220m   |___/  |_|  |___|  \\___//_/ \\_\\|___/  \\___/  \\___/\033[0m"
     echo -e "\033[0;90m · .  · .  *  · .  *  · .  *  · .  *  · .  *  · .  ·\033[0m"
     echo -e "\033[38;5;93m══════════════\033[38;5;99m══════════════\033[38;5;105m══════════════\033[38;5;117m══════════════\033[0m"
-    echo -e " \033[0;32m●\033[0m Stegasoo is running"
-    echo -e "   \033[0;33m$STEGASOO_URL\033[0m"
     # Show CPU stats if overclocked (read configured freq, not current idle freq)
     CONFIG_FILE=""
     if [ -f /boot/firmware/config.txt ]; then CONFIG_FILE="/boot/firmware/config.txt"
     elif [ -f /boot/config.txt ]; then CONFIG_FILE="/boot/config.txt"; fi
+    CPU_MHZ=""
+    CPU_TEMP=""
     if [ -n "$CONFIG_FILE" ] && grep -qE "^arm_freq=" "$CONFIG_FILE" 2>/dev/null; then
         CPU_MHZ=$(grep "^arm_freq=" "$CONFIG_FILE" | cut -d= -f2)
         CPU_TEMP=$(vcgencmd measure_temp 2>/dev/null | cut -d= -f2)
+    fi
+    # Compact two-column layout
+    echo -e " 🚀 Stegasoo running     🌐 \033[0;33m$STEGASOO_URL\033[0m"
     if [ -n "$CPU_MHZ" ] && [ -n "$CPU_TEMP" ]; then
-            echo -e "   \033[0;35m⚡\033[0m ${CPU_MHZ} MHz  \033[0;35m🌡\033[0m ${CPU_TEMP}"
+        # Temp emoji: ice<50, cool 50-70, fire>70
+        TEMP_NUM=$(echo "$CPU_TEMP" | grep -oE "[0-9]+" | head -1)
+        if [ -n "$TEMP_NUM" ]; then
+            if [ "$TEMP_NUM" -ge 70 ]; then
+                TEMP_EMOJI="🔥"
+            elif [ "$TEMP_NUM" -ge 50 ]; then
+                TEMP_EMOJI="😎"
+            else
+                TEMP_EMOJI="🧊"
             fi
+        else
+            TEMP_EMOJI="🌡"
         fi
+        echo -e " \033[0;35m⚡\033[0m ${CPU_MHZ} MHz             ${TEMP_EMOJI} ${CPU_TEMP}"
+    fi
+    echo -e "\033[38;5;93m══════════════\033[38;5;99m══════════════\033[38;5;105m══════════════\033[38;5;117m══════════════\033[0m"
     echo ""
 else
     echo ""
@@ -448,6 +481,10 @@ MOTDEOF
 sudo chmod 644 /etc/profile.d/stegasoo-motd.sh
 echo "  Created login banner"
 
+# Shorten the default Debian MOTD boilerplate
+echo "Debian GNU/Linux · License: /usr/share/doc/*/copyright" | sudo tee /etc/motd > /dev/null
+echo "  Shortened system MOTD"
+
 echo ""
 echo -e "${BOLD}Installation Complete!${NC}"
 echo -e "${BLUE}-------------------------------------------------------${NC}"
@@ -613,15 +650,19 @@ echo -e "${BLUE}-------------------------------------------------------${NC}"
 echo ""
 
 PI_IP=$(hostname -I | awk '{print $1}')
+PI_HOST=$(hostname)
 
 echo -e "${GREEN}Create your admin account:${NC}"
 if [ "$ENABLE_HTTPS" = "true" ]; then
     if [ "$USE_PORT_443" = "true" ]; then
+        echo -e "  ${YELLOW}https://$PI_HOST.local/setup${NC}"
         echo -e "  ${YELLOW}https://$PI_IP/setup${NC}"
     else
+        echo -e "  ${YELLOW}https://$PI_HOST.local:5000/setup${NC}"
         echo -e "  ${YELLOW}https://$PI_IP:5000/setup${NC}"
     fi
 else
+    echo -e "  ${YELLOW}http://$PI_HOST.local:5000/setup${NC}"
     echo -e "  ${YELLOW}http://$PI_IP:5000/setup${NC}"
 fi
 
@@ -649,12 +690,12 @@ if [[ ! $REPLY =~ ^[Nn]$ ]]; then
         echo -e "${GREEN}✓ Stegasoo is running!${NC}"
         if [ "$ENABLE_HTTPS" = "true" ]; then
             if [ "$USE_PORT_443" = "true" ]; then
-                echo -e "  Create admin: ${YELLOW}https://$PI_IP/setup${NC}"
+                echo -e "  Create admin: ${YELLOW}https://$PI_HOST.local/setup${NC} or ${YELLOW}https://$PI_IP/setup${NC}"
             else
-                echo -e "  Create admin: ${YELLOW}https://$PI_IP:5000/setup${NC}"
+                echo -e "  Create admin: ${YELLOW}https://$PI_HOST.local:5000/setup${NC} or ${YELLOW}https://$PI_IP:5000/setup${NC}"
             fi
         else
-            echo -e "  Create admin: ${YELLOW}http://$PI_IP:5000/setup${NC}"
+            echo -e "  Create admin: ${YELLOW}http://$PI_HOST.local:5000/setup${NC} or ${YELLOW}http://$PI_IP:5000/setup${NC}"
         fi
     else
         echo -e "${RED}✗ Failed to start. Check logs:${NC} journalctl -u stegasoo -f"

src/stegasoo/cli.py

@@ -1,7 +1,69 @@
 """
 Stegasoo CLI Module (v3.2.0)
 
-Command-line interface with batch processing and compression support.
+A proper CLI architecture using Click. This module demonstrates several
+important patterns for building production-quality command-line tools:
+
+PATTERN: COMMAND GROUPS
+=======================
+Click's @group decorator creates a hierarchy of commands:
+
+    stegasoo                     <- Main entry point
+    ├── encode                   <- Simple commands at root level
+    ├── decode
+    ├── generate
+    ├── info
+    ├── batch/                   <- Group for related commands
+    │   ├── encode
+    │   ├── decode
+    │   └── check
+    ├── channel/                 <- Another group
+    │   ├── generate
+    │   ├── show
+    │   ├── status
+    │   ├── qr
+    │   └── clear
+    ├── tools/                   <- Utility group
+    │   ├── capacity
+    │   ├── strip
+    │   ├── peek
+    │   └── exif
+    └── admin/                   <- Administration group
+        ├── recover
+        └── generate-key
+
+PATTERN: JSON OUTPUT MODE
+=========================
+Every command supports --json for machine-readable output. The pattern:
+
+    @click.pass_context
+    def my_command(ctx, ...):
+        if ctx.obj.get("json"):
+            click.echo(json.dumps(result, indent=2))
+        else:
+            # Human-readable output with colors/formatting
+            click.echo(f"✓ Success: {result}")
+
+This makes the CLI scriptable - you can pipe to jq, use in shell scripts, etc.
+
+PATTERN: SENSITIVE INPUT
+========================
+Passwords/secrets use Click's secure prompts:
+
+    @click.option("--passphrase", prompt=True, hide_input=True,
+                  confirmation_prompt=True, help="Passphrase")
+
+- prompt=True: Asks if not provided
+- hide_input=True: No echo (like sudo)
+- confirmation_prompt=True: "Repeat for confirmation"
+
+PATTERN: DRY-RUN MODE
+=====================
+For destructive or slow operations, --dry-run shows what WOULD happen:
+
+    if dry_run:
+        click.echo(f"Would encode to {output}")
+        return
 
 Changes in v3.2.0:
 - Updated to use DEFAULT_PASSPHRASE_WORDS (consistency with v3.2.0 naming)
@@ -32,10 +94,23 @@ from .constants import (
     __version__,
 )
 
-# Click context settings
+# Click context settings - these apply to all commands
+# help_option_names lets users use either -h or --help
 CONTEXT_SETTINGS = dict(help_option_names=["-h", "--help"])
 
 
+# =============================================================================
+# ROOT GROUP - The main entry point
+# =============================================================================
+#
+# @click.group() creates a command group. The function becomes both:
+# 1. A callable that sets up shared state (ctx.obj)
+# 2. A container for subcommands via @cli.command() decorators
+#
+# The context object (ctx.obj) is passed down to all subcommands.
+# We use it to share the --json flag across the entire CLI.
+
+
 @click.group(context_settings=CONTEXT_SETTINGS)
 @click.version_option(__version__, "-v", "--version")
 @click.option("--json", "json_output", is_flag=True, help="Output results as JSON")
@@ -46,6 +121,8 @@ def cli(ctx, json_output):
 
     Hide messages in images using PIN + passphrase security.
     """
+    # ensure_object(dict) creates ctx.obj if it doesn't exist
+    # This prevents "NoneType has no attribute" errors
     ctx.ensure_object(dict)
     ctx.obj["json"] = json_output
 
@@ -53,6 +130,31 @@ def cli(ctx, json_output):
 # =============================================================================
 # ENCODE COMMANDS
 # =============================================================================
+#
+# The encode command demonstrates several Click patterns:
+#
+# 1. ARGUMENT vs OPTION
+#    - Arguments are positional: `stegasoo encode photo.png`
+#    - Options have flags: `stegasoo encode -m "message" --pin 1234`
+#    Rule of thumb: required inputs → arguments, optional/secret → options
+#
+# 2. MUTUAL EXCLUSIVITY
+#    We need either --message OR --file, not both. Click doesn't have built-in
+#    mutual exclusivity, so we check manually:
+#
+#        if not message and not file_payload:
+#            raise click.UsageError("Either --message or --file is required")
+#
+# 3. TYPE VALIDATION
+#    Click validates types automatically:
+#    - type=click.Path(exists=True) → file must exist
+#    - type=click.Choice(["a", "b"]) → must be one of these values
+#    - type=int → must be an integer
+#
+# 4. DEFAULT VALUES
+#    Options can have smart defaults:
+#    - default="zlib" → use this if not specified
+#    - default=True with is_flag=True → boolean flag defaults to on
 
 
 @cli.command()
@@ -320,6 +422,32 @@ def decode(ctx, image, reference, passphrase, pin, output):
 # =============================================================================
 # BATCH COMMANDS
 # =============================================================================
+#
+# Batch processing demonstrates:
+#
+# 1. SUBGROUPS
+#    @cli.group() creates a nested command group:
+#        stegasoo batch encode *.png
+#        stegasoo batch decode *.png
+#        stegasoo batch check *.png
+#
+# 2. VARIADIC ARGUMENTS
+#    nargs=-1 accepts multiple arguments:
+#        @click.argument("images", nargs=-1, required=True)
+#    This lets users do: `stegasoo batch encode img1.png img2.png img3.png`
+#    Or with shell expansion: `stegasoo batch encode *.png`
+#
+# 3. PROGRESS CALLBACKS
+#    We pass a callback to the BatchProcessor for real-time updates:
+#
+#        def progress(current, total, item):
+#            click.echo(f"[{current}/{total}] {item.input_path.name}")
+#
+#        processor.batch_encode(..., progress_callback=progress)
+#
+# 4. PARALLEL PROCESSING
+#    --jobs/-j controls worker count. Default is 4 for good balance between
+#    speed and memory usage. Each worker loads images into memory.
 
 
 @cli.group()
@@ -595,10 +723,10 @@ def info(ctx, full):
 
     # Check for DCT support
     try:
-        from .dct_steganography import HAS_SCIPY, HAS_JPEGIO
+        from .dct_steganography import HAS_JPEGIO, HAS_SCIPY
-        HAS_DCT = HAS_SCIPY and HAS_JPEGIO
+        has_dct = HAS_SCIPY and HAS_JPEGIO
     except ImportError:
-        HAS_DCT = False
+        has_dct = False
 
     # Check service status
     service_status = "unknown"
@@ -637,7 +765,7 @@ def info(ctx, full):
     channel_fingerprint = None
     channel_source = None
     try:
-        from .channel import get_channel_key, get_channel_fingerprint, get_channel_status
+        from .channel import get_channel_fingerprint, get_channel_key, get_channel_status
         key = get_channel_key()
         if key:
             channel_fingerprint = get_channel_fingerprint(key)
@@ -688,7 +816,7 @@ def info(ctx, full):
         "version": __version__,
         "service": service_status,
         "url": service_url,
-        "dct_support": HAS_DCT,
+        "dct_support": has_dct,
         "channel": {
             "fingerprint": channel_fingerprint,
             "source": channel_source,
@@ -718,11 +846,11 @@ def info(ctx, full):
 
         # Service status
         if service_status == "active":
-            click.echo(f"  Service:     \033[32m● running\033[0m")
+            click.echo("  Service:     \033[32m● running\033[0m")
             if service_url:
                 click.echo(f"  URL:         {service_url}")
         elif service_status == "inactive":
-            click.echo(f"  Service:     \033[31m○ stopped\033[0m")
+            click.echo("  Service:     \033[31m○ stopped\033[0m")
         else:
             click.echo(f"  Service:     \033[33m? {service_status}\033[0m")
 
@@ -731,10 +859,10 @@ def info(ctx, full):
             masked = f"{channel_fingerprint[:4]}••••••••{channel_fingerprint[-4:]}"
             click.echo(f"  Channel:     {masked}")
         else:
-            click.echo(f"  Channel:     \033[33mpublic\033[0m")
+            click.echo("  Channel:     \033[33mpublic\033[0m")
 
         # DCT
-        dct_status = "\033[32m✓ enabled\033[0m" if HAS_DCT else "\033[31m✗ disabled\033[0m"
+        dct_status = "\033[32m✓ enabled\033[0m" if has_dct else "\033[31m✗ disabled\033[0m"
         click.echo(f"  DCT:         {dct_status}")
 
         # System info (if --full)

src/stegasoo/constants.py

@@ -25,7 +25,7 @@ from pathlib import Path
 # VERSION
 # ============================================================================
 
-__version__ = "4.1.3"
+__version__ = "4.1.5"
 
 # ============================================================================
 # FILE FORMAT

src/stegasoo/crypto.py

@@ -1,18 +1,26 @@
 """
 Stegasoo Cryptographic Functions (v4.0.0 - Channel Key Support)
 
-Key derivation, encryption, and decryption using AES-256-GCM.
+This is the crypto layer - where we turn plaintext into indecipherable noise.
-Supports both text messages and binary file payloads.
 
-BREAKING CHANGES in v4.0.0:
+The security model is multi-factor:
-- Added channel key support for deployment/group isolation
+┌────────────────────────────────────────────────────────────────────┐
-- Messages encoded with a channel key require the same key to decode
+│  SOMETHING YOU HAVE          SOMETHING YOU KNOW                    │
-- Channel key can be configured via environment, config file, or explicit parameter
+│  ├─ Reference photo          ├─ Passphrase (4+ BIP-39 words)      │
-- FORMAT_VERSION bumped to 5
+│  └─ RSA private key (opt)    └─ PIN (6-9 digits)                  │
+│                                                                    │
+│  DEPLOYMENT BINDING                                                │
+│  └─ Channel key (ties messages to a specific server/group)        │
+└────────────────────────────────────────────────────────────────────┘
 
-BREAKING CHANGES in v3.2.0:
+All factors get mixed together through Argon2id (memory-hard KDF) to derive
-- Removed date dependency from key derivation
+the actual encryption key. Miss any factor = wrong key = garbage output.
-- Renamed day_phrase → passphrase (no daily rotation needed)
+
+Encryption: AES-256-GCM (authenticated encryption - tamper = detection)
+KDF: Argon2id (256MB RAM, 4 iterations) or PBKDF2 fallback (600K iterations)
+
+v4.0.0: Added channel key for server/group isolation
+v3.2.0: Removed date dependency (was cute but annoying in practice)
 """
 
 import hashlib
@@ -98,25 +106,38 @@ def _resolve_channel_key(channel_key: str | bool | None) -> bytes | None:
 # =============================================================================
 # CORE CRYPTO FUNCTIONS
 # =============================================================================
+#
+# The "reference photo as a key" concept is one of Stegasoo's unique features.
+# Most steganography tools just use a password. We add the photo as a
+# "something you have" factor - like a hardware token, but it's a cat picture.
 
 
 def hash_photo(image_data: bytes) -> bytes:
     """
     Compute deterministic hash of photo pixel content.
 
-    This normalizes the image to RGB and hashes the raw pixel data,
+    This is the magic sauce that turns your cat photo into a cryptographic key.
-    making it resistant to metadata changes.
+
+    Why pixels and not the file hash?
+    - File metadata changes (EXIF stripped, resaved) = different file hash
+    - But pixel content stays the same
+    - We hash the RGB values directly, so format conversions don't matter
+
+    The double-hash with prefix is belt-and-suspenders mixing. Probably
+    overkill, but hey, it's crypto - paranoia is a feature.
 
     Args:
-        image_data: Raw image file bytes
+        image_data: Raw image file bytes (any format PIL can read)
 
     Returns:
-        32-byte SHA-256 hash
+        32-byte SHA-256 hash of pixel content
     """
+    # Convert to RGB to normalize (RGBA, grayscale, etc. all become RGB)
     img: Image.Image = Image.open(io.BytesIO(image_data)).convert("RGB")
     pixels = img.tobytes()
 
-    # Double-hash with prefix for additional mixing
+    # Double-hash: SHA256(SHA256(pixels) + first 1KB of pixels)
+    # The prefix adds image-specific data to prevent length-extension shenanigans
     h = hashlib.sha256(pixels).digest()
     h = hashlib.sha256(h + pixels[:1024]).digest()
     return h
@@ -133,20 +154,38 @@ def derive_hybrid_key(
     """
     Derive encryption key from multiple factors.
 
-    Combines:
+    This is the heart of Stegasoo's security model. We take all the things
-    - Photo hash (something you have)
+    you need to prove you're authorized (photo, passphrase, PIN, etc.) and
-    - Passphrase (something you know)
+    blend them together into one 32-byte key.
-    - PIN (something you know, static)
-    - RSA key (something you have)
-    - Channel key (deployment/group binding)
-    - Salt (random per message)
 
-    Uses Argon2id if available, falls back to PBKDF2.
+    The flow:
+    ┌─────────────┐   ┌─────────────┐   ┌─────────────┐
+    │ Photo hash  │ + │ passphrase  │ + │ PIN + RSA   │ + salt
+    └─────────────┘   └─────────────┘   └─────────────┘
+           │                 │                 │
+           └────────────────┴────────────────┘
+                             │
+                             ▼
+                    ┌─────────────────┐
+                    │    Argon2id     │  <- Memory-hard KDF
+                    │   256MB / 4 iter │  <- Makes brute force expensive
+                    └─────────────────┘
+                             │
+                             ▼
+                      32-byte AES key
+
+    Why Argon2id?
+    - Memory-hard: attackers can't just throw GPUs at it
+    - 256MB RAM per attempt = expensive at scale
+    - Winner of the Password Hashing Competition (2015)
+    - "id" variant resists both side-channel and GPU attacks
+
+    Fallback: PBKDF2-SHA512 with 600K iterations (for systems without argon2)
 
     Args:
         photo_data: Reference photo bytes
-        passphrase: Shared passphrase (recommend 4+ words)
+        passphrase: Shared passphrase (recommend 4+ words from BIP-39)
-        salt: Random salt for this message
+        salt: Random salt for this message (32 bytes)
         pin: Optional static PIN
         rsa_key_data: Optional RSA key bytes
         channel_key: Channel key parameter:
@@ -155,7 +194,7 @@ def derive_hybrid_key(
             - "" or False: No channel key (public mode)
 
     Returns:
-        32-byte derived key
+        32-byte derived key (ready for AES-256)
 
     Raises:
         KeyDerivationError: If key derivation fails
@@ -163,31 +202,36 @@ def derive_hybrid_key(
     try:
         photo_hash = hash_photo(photo_data)
 
-        # Resolve channel key
+        # Resolve channel key (server-specific binding)
         channel_hash = _resolve_channel_key(channel_key)
 
-        # Build key material
+        # Build key material by concatenating all factors
+        # Passphrase is lowercased to be forgiving of case differences
         key_material = photo_hash + passphrase.lower().encode() + pin.encode() + salt
 
-        # Add RSA key hash if provided
+        # Add RSA key hash if provided (another "something you have")
         if rsa_key_data:
             key_material += hashlib.sha256(rsa_key_data).digest()
 
-        # Add channel key hash if configured (v4.0.0)
+        # Add channel key hash if configured (v4.0.0 - deployment binding)
         if channel_hash:
             key_material += channel_hash
 
+        # Run it all through the KDF
         if HAS_ARGON2:
+            # Argon2id: the good stuff
             key = hash_secret_raw(
                 secret=key_material,
                 salt=salt[:32],
-                time_cost=ARGON2_TIME_COST,
+                time_cost=ARGON2_TIME_COST,      # 4 iterations
-                memory_cost=ARGON2_MEMORY_COST,
+                memory_cost=ARGON2_MEMORY_COST,  # 256 MB RAM
-                parallelism=ARGON2_PARALLELISM,
+                parallelism=ARGON2_PARALLELISM,  # 4 threads
                 hash_len=32,
-                type=Type.ID,
+                type=Type.ID,  # Hybrid mode: resists side-channel AND GPU attacks
             )
         else:
+            # PBKDF2 fallback for systems without argon2-cffi
+            # 600K iterations is slow but not memory-hard
             kdf = PBKDF2HMAC(
                 algorithm=hashes.SHA512(),
                 length=32,
@@ -347,9 +391,12 @@ def _unpack_payload(data: bytes) -> DecodeResult:
 # =============================================================================
 # HEADER FLAGS (v4.0.0)
 # =============================================================================
+#
+# The flags byte tells us about the message without decrypting it.
+# Currently just one flag, but the byte gives us room for 8.
 
-# Header flag bits
+FLAG_CHANNEL_KEY = 0x01  # Bit 0: Message was encoded with a channel key
-FLAG_CHANNEL_KEY = 0x01  # Set if encoded with a channel key
+# Future flags could include: compression, file attachment, etc.
 
 
 def encrypt_message(
@@ -361,33 +408,40 @@ def encrypt_message(
     channel_key: str | bool | None = None,
 ) -> bytes:
     """
-    Encrypt message or file using AES-256-GCM with hybrid key derivation.
+    Encrypt message or file using AES-256-GCM.
 
-    Message format (v4.0.0 - with channel key support):
+    This is where plaintext becomes ciphertext. We use AES-256-GCM which is:
-    - Magic header (4 bytes)
+    - AES: The standard, used by everyone from banks to governments
-    - Version (1 byte) = 5
+    - 256-bit key: Enough entropy to survive until the heat death of the universe
-    - Flags (1 byte) - indicates if channel key was used
+    - GCM mode: Authenticated encryption - if anyone tampers, decryption fails
-    - Salt (32 bytes)
+
-    - IV (12 bytes)
+    The output format (v4.0.0):
-    - Auth tag (16 bytes)
+    ┌──────────────────────────────────────────────────────────────────────┐
-    - Ciphertext (variable, padded)
+    │ \x89ST3 │ 05 │ flags │  salt (32B)  │  iv (12B)  │  tag (16B)  │ ··· │
+    │  magic  │ver │       │              │            │             │cipher│
+    └──────────────────────────────────────────────────────────────────────┘
+
+    Why the random padding at the end?
+    - Message length can reveal information (traffic analysis)
+    - We add 64-319 random bytes and round to 256-byte boundary
+    - All messages look roughly the same size
 
     Args:
         message: Message string, raw bytes, or FilePayload to encrypt
-        photo_data: Reference photo bytes
+        photo_data: Reference photo bytes (your "key photo")
-        passphrase: Shared passphrase (recommend 4+ words for good entropy)
+        passphrase: Shared passphrase (recommend 4+ words from BIP-39)
-        pin: Optional static PIN
+        pin: Optional static PIN for additional security
-        rsa_key_data: Optional RSA key bytes
+        rsa_key_data: Optional RSA key bytes (another "something you have")
         channel_key: Channel key parameter:
-            - None or "auto": Use configured key
+            - None or "auto": Use server's configured key
             - str: Use this specific key
             - "" or False: No channel key (public mode)
 
     Returns:
-        Encrypted message bytes
+        Encrypted message bytes ready for embedding
 
     Raises:
-        EncryptionError: If encryption fails
+        EncryptionError: If encryption fails (shouldn't happen with valid inputs)
     """
     try:
         salt = secrets.token_bytes(SALT_SIZE)

src/stegasoo/dct_steganography.py

@@ -1,22 +1,30 @@
 """
 DCT Domain Steganography Module (v4.1.0)
 
-Embeds data in DCT coefficients with two approaches:
+The fancy pants mode. Instead of hiding bits in pixel values (LSB mode),
-1. PNG output: Scipy-based DCT transform (grayscale or color)
+we hide them in the *frequency domain* - specifically in the Discrete Cosine
-2. JPEG output: jpegio-based coefficient manipulation (if available)
+Transform coefficients that JPEG compression uses internally.
 
-v4.1.0 Changes:
+Why is this cool?
-- Reed-Solomon error correction protects against bit errors in problematic blocks
+- Survives some image processing that would destroy LSB data
-- Majority voting on length headers (3 copies) for additional robustness
+- Works with JPEG without the usual "save destroys everything" problem
-- RS can correct up to 16 byte errors per 223-byte chunk
+- Uses the same math that JPEG itself uses - we're hiding in plain sight
 
-v3.2.0-patch2 Changes:
+Two approaches depending on what you want:
-- Chunked processing for large images to avoid heap corruption
+1. PNG output: We do our own DCT math via scipy (works on any image)
-- Process image in vertical strips to limit memory per operation
+2. JPEG output: We use jpegio to directly tweak the coefficients (chef's kiss)
-- Isolated DCT operations with fresh array allocations
-- Workaround for scipy.fftpack memory issues
 
-Requires: scipy (for PNG mode), optionally jpegio (for JPEG mode), reedsolo (for error correction)
+v4.1.0 - The "please stop corrupting my data" release:
+- Reed-Solomon error correction (can fix up to 16 byte errors per chunk)
+- Majority voting on headers (store 3 copies, take the winner)
+- Because some image regions are just... problematic
+
+v3.2.0-patch2 - The "scipy why are you like this" release:
+- Chunked processing because scipy's FFT was corrupting memory on big images
+- Process blocks one at a time with fresh arrays
+- Yes, it's slower. No, I don't care. Correctness > speed.
+
+Requires: scipy (PNG mode), optionally jpegio (JPEG mode), reedsolo (error correction)
 """
 
 import gc
@@ -87,11 +95,31 @@ def _write_progress(progress_file: str | None, current: int, total: int, phase:
 # CONSTANTS
 # ============================================================================
 
+# JPEG uses 8x8 blocks for DCT - this is baked into the standard
 BLOCK_SIZE = 8
+
+# The zig-zag order of DCT coefficients. JPEG stores them this way because
+# the human eye is more sensitive to low frequencies (top-left corner)
+# than high frequencies (bottom-right). After quantization, most high-freq
+# coefficients become zero, so zig-zag gives great compression.
+#
+# Visual of an 8x8 DCT block with zig-zag numbering:
+#
+#   DC  1   5   6  14  15  27  28     <- Low frequency (smooth gradients)
+#    2  4   7  13  16  26  29  42
+#    3  8  12  17  25  30  41  43
+#    9 11  18  24  31  40  44  53
+#   10 19  23  32  39  45  52  54
+#   20 22  33  38  46  51  55  60
+#   21 34  37  47  50  56  59  61
+#   35 36  48  49  57  58  62  63     <- High frequency (fine detail/noise)
+#
+# Position (0,0) is the DC coefficient - the average brightness of the block.
+# We NEVER touch DC because changing it causes visible brightness shifts.
 EMBED_POSITIONS = [
-    (0, 1),
+    (0, 1),   # 1st AC coefficient
-    (1, 0),
+    (1, 0),   # 2nd AC coefficient
-    (2, 0),
+    (2, 0),   # ... and so on in zig-zag order
     (1, 1),
     (0, 2),
     (0, 3),
@@ -124,32 +152,59 @@ EMBED_POSITIONS = [
     (6, 1),
     (7, 0),
 ]
+
+# We use positions 4-20 (mid-frequency range). Here's the reasoning:
+# - Positions 0-3: Too low frequency, changes are visible as color shifts
+# - Positions 4-20: Sweet spot - carries enough energy to survive, not visible
+# - Positions 21+: High frequency, often quantized to zero, unreliable
 DEFAULT_EMBED_POSITIONS = EMBED_POSITIONS[4:20]
+
+# Quantization step for QIM (Quantization Index Modulation).
+# This is how we actually embed bits: we round the coefficient to a grid
+# and then nudge it based on whether we want a 0 or 1.
+# Bigger step = more robust to noise, but more visible. 25 is a good balance.
 QUANT_STEP = 25
-DCT_MAGIC = b"DCTS"
+
-HEADER_SIZE = 10
+# Magic bytes so we can identify our own images
+DCT_MAGIC = b"DCTS"      # scipy DCT mode marker
+JPEGIO_MAGIC = b"JPGS"   # jpegio native JPEG mode marker
+HEADER_SIZE = 10         # Magic (4) + version (1) + flags (1) + length (4)
+
 OUTPUT_FORMAT_PNG = "png"
 OUTPUT_FORMAT_JPEG = "jpeg"
-JPEG_OUTPUT_QUALITY = 95
+JPEG_OUTPUT_QUALITY = 95  # High quality but not 100 (100 causes issues, see below)
-JPEGIO_MAGIC = b"JPGS"
+
+# For jpegio mode: we only embed in coefficients with magnitude >= 2
+# Coefficients of 0 or 1 are usually quantized noise - unreliable
 JPEGIO_MIN_COEF_MAGNITUDE = 2
+
+# We embed in the Y (luminance) channel only - it has the most capacity
+# Cb/Cr are often subsampled 4:2:0 anyway
 JPEGIO_EMBED_CHANNEL = 0
-FLAG_COLOR_MODE = 0x01
-FLAG_RS_PROTECTED = 0x02  # Reed-Solomon error correction enabled
 
-# Reed-Solomon settings - 32 symbols can correct up to 16 byte errors per 223-byte chunk
+# Header flags
+FLAG_COLOR_MODE = 0x01      # Set if we preserved color (YCbCr mode)
+FLAG_RS_PROTECTED = 0x02    # Set if Reed-Solomon protected (v4.1.0+)
+
+# Reed-Solomon settings - the "please don't lose my data" system
+# 32 parity symbols per chunk means we can correct up to 16 byte errors
+# Math: RS(255, 223) where 255-223=32 parity bytes, corrects floor(32/2)=16
 RS_NSYM = 32
-RS_LENGTH_HEADER_SIZE = 8  # 8 bytes: 4 for raw_payload_length + 4 for rs_payload_length
-RS_LENGTH_COPIES = 3  # Store length header 3 times for majority voting
-RS_LENGTH_PREFIX_SIZE = RS_LENGTH_HEADER_SIZE * RS_LENGTH_COPIES  # Total: 24 bytes
 
-# Chunking settings for large images
+# We store the payload length 3 times and take majority vote
-MAX_CHUNK_HEIGHT = 512  # Process in 512-pixel tall strips
+# Because if the length is wrong, everything is wrong
+RS_LENGTH_HEADER_SIZE = 8   # 4 bytes raw length + 4 bytes RS-encoded length
+RS_LENGTH_COPIES = 3        # Store 3 copies, need 2 to agree
+RS_LENGTH_PREFIX_SIZE = RS_LENGTH_HEADER_SIZE * RS_LENGTH_COPIES  # 24 bytes total
 
-# JPEG normalization settings
+# Chunking for large images - scipy's FFT gets memory-corrupty on huge arrays
-# JPEGs with quality=100 have all quantization values = 1, which crashes jpegio
+MAX_CHUNK_HEIGHT = 512  # Process in strips to keep memory sane
-JPEGIO_NORMALIZE_QUALITY = 95  # Re-save quality for problematic JPEGs
+
-JPEGIO_MAX_QUANT_VALUE_THRESHOLD = 1  # If all quant values <= this, normalize
+# Fun bug: JPEGs saved with quality=100 have quantization tables full of 1s
+# This makes the DCT coefficients HUGE and jpegio crashes spectacularly
+# Solution: detect and re-save at quality 95 first
+JPEGIO_NORMALIZE_QUALITY = 95
+JPEGIO_MAX_QUANT_VALUE_THRESHOLD = 1  # All 1s in quant table = bad news
 
 
 # ============================================================================
@@ -209,13 +264,26 @@ def has_jpegio_support() -> bool:
 
 # ============================================================================
 # REED-SOLOMON ERROR CORRECTION
-# Protects against bit errors in problematic image blocks
 # ============================================================================
+#
+# Why do we need this? DCT embedding isn't perfect. Some image regions are
+# problematic - flat areas, high compression, edge cases. Bits can flip.
+#
+# Reed-Solomon is the same error correction used in CDs, DVDs, QR codes, and
+# deep space communications. If it's good enough for Voyager, it's good enough
+# for hiding cat pictures in other cat pictures.
+#
+# How it works (simplified):
+# 1. Take your data bytes
+# 2. Add extra "parity" bytes calculated from the data
+# 3. If some bytes get corrupted, the math lets you reconstruct them
+# 4. RS(255, 223) means: 255 byte blocks, 223 data + 32 parity
+# 5. Can correct up to 16 corrupted bytes per block (floor(32/2))
+#
+# The tradeoff: ~14% overhead (32/223). Worth it for reliability.
 
-# Check for reedsolo availability
 try:
     from reedsolo import ReedSolomonError, RSCodec
-
     HAS_REEDSOLO = True
 except ImportError:
     HAS_REEDSOLO = False
@@ -224,48 +292,78 @@ except ImportError:
 
 
 def _rs_encode(data: bytes) -> bytes:
-    """Add Reed-Solomon error correction symbols to data."""
+    """
+    Wrap data in Reed-Solomon error correction.
+
+    Takes your precious payload and adds parity bytes so we can
+    recover from the inevitable bit-rot of DCT embedding.
+    """
     if not HAS_REEDSOLO:
-        return data  # No protection if reedsolo not available
+        return data  # YOLO mode - no protection, good luck
     rs = RSCodec(RS_NSYM)
     return bytes(rs.encode(data))
 
 
 def _rs_decode(data: bytes) -> bytes:
-    """Decode Reed-Solomon protected data, correcting errors if possible."""
+    """
+    Decode Reed-Solomon protected data, fixing errors along the way.
+
+    This is where the magic happens. If bits got flipped during
+    extraction, RS will quietly fix them. If too many flipped...
+    well, we tried.
+    """
     if not HAS_REEDSOLO:
-        return data  # No decoding if reedsolo not available
+        return data
     rs = RSCodec(RS_NSYM)
     try:
         decoded, _, errata_pos = rs.decode(data)
         if errata_pos:
-            pass  # Errors were corrected
+            # Errors were found and corrected - RS earned its keep today
+            pass
         return bytes(decoded)
     except ReedSolomonError as e:
+        # Too many errors - the image got mangled beyond repair
         raise StegasooRSError(f"Image corrupted beyond repair: {e}") from e
 
 
 # ============================================================================
 # SAFE DCT FUNCTIONS
-# These create fresh arrays to avoid scipy memory corruption issues
 # ============================================================================
+#
+# Story time: scipy's fftpack (the old DCT implementation) has memory issues
+# when you process large images. We'd get random garbage in our output, or
+# worse, segfaults. Turns out it was reusing internal buffers in unsafe ways.
+#
+# The fix? Be paranoid. Every single array operation creates a fresh copy.
+# Is it slower? Yes. Does it work? Also yes. I'll take correct over fast.
+#
+# The newer scipy.fft module is better, but we still play it safe because
+# not everyone has the latest scipy and I don't want debugging nightmares.
 
 
 def _safe_dct2(block: np.ndarray) -> np.ndarray:
     """
-    Apply 2D DCT with memory isolation.
+    Apply 2D DCT (Discrete Cosine Transform) to an 8x8 block.
-    Creates a completely fresh array to avoid heap corruption.
+
+    The DCT converts spatial data (pixel values) into frequency data
+    (how much of each frequency component is present). It's the heart
+    of JPEG compression.
+
+    We do it row-by-row and column-by-column with fresh arrays each time
+    because scipy's built-in dct2 can corrupt memory on large batches.
+    Paranoid? Yes. Necessary? Also yes.
     """
-    # Create a brand new array (not a view)
+    # Create a brand new array (not a view) - paranoia level: maximum
     safe_block = np.array(block, dtype=np.float64, copy=True, order="C")
 
-    # First DCT on columns (transpose -> DCT rows -> transpose back)
+    # 2D DCT = 1D DCT on rows, then 1D DCT on columns (separable transform)
+    # First pass: DCT each column
     temp = np.zeros_like(safe_block, dtype=np.float64, order="C")
     for i in range(BLOCK_SIZE):
         col = np.array(safe_block[:, i], dtype=np.float64, copy=True)
-        temp[:, i] = dct(col, norm="ortho")
+        temp[:, i] = dct(col, norm="ortho")  # ortho normalization for symmetry
 
-    # Second DCT on rows
+    # Second pass: DCT each row of the result
     result = np.zeros_like(temp, dtype=np.float64, order="C")
     for i in range(BLOCK_SIZE):
         row = np.array(temp[i, :], dtype=np.float64, copy=True)
@@ -276,19 +374,22 @@ def _safe_dct2(block: np.ndarray) -> np.ndarray:
 
 def _safe_idct2(block: np.ndarray) -> np.ndarray:
     """
-    Apply 2D inverse DCT with memory isolation.
+    Apply 2D inverse DCT - convert frequency data back to pixels.
-    Creates a completely fresh array to avoid heap corruption.
+
+    After we've embedded our secret bits in the DCT coefficients,
+    we need to convert back to pixel values. This is the reverse
+    of _safe_dct2.
+
+    Same paranoid memory handling because same paranoid developer.
     """
-    # Create a brand new array (not a view)
     safe_block = np.array(block, dtype=np.float64, copy=True, order="C")
 
-    # First IDCT on rows
+    # Inverse is the same idea: IDCT rows, then IDCT columns
     temp = np.zeros_like(safe_block, dtype=np.float64, order="C")
     for i in range(BLOCK_SIZE):
         row = np.array(safe_block[i, :], dtype=np.float64, copy=True)
         temp[i, :] = idct(row, norm="ortho")
 
-    # Second IDCT on columns
     result = np.zeros_like(temp, dtype=np.float64, order="C")
     for i in range(BLOCK_SIZE):
         col = np.array(temp[:, i], dtype=np.float64, copy=True)
@@ -348,8 +449,25 @@ def _unpad_image(image: np.ndarray, original_size: tuple[int, int]) -> np.ndarra
 
 
 def _embed_bit_in_coeff(coef: float, bit: int, quant_step: int = QUANT_STEP) -> float:
+    """
+    Embed a single bit into a DCT coefficient using QIM.
+
+    QIM (Quantization Index Modulation) is smarter than simple LSB flipping.
+    Instead of just changing the last bit, we round to a quantization grid
+    and use odd/even to encode 0/1.
+
+    Why is this better?
+    - More robust to noise (small changes don't flip the bit)
+    - Works naturally with JPEG's own quantization
+    - The change is spread across the coefficient's magnitude
+
+    Visual example (quant_step=25):
+    - Coef = 73, want bit=0 -> round to 75 (75/25=3, 3%2=1) -> nudge to 50 (50/25=2, 2%2=0)
+    - Coef = 73, want bit=1 -> round to 75 (75/25=3, 3%2=1) -> already odd, keep at 75
+    """
     quantized = round(coef / quant_step)
     if (quantized % 2) != bit:
+        # Need to flip even<->odd. Nudge in the direction that's closest.
         if quantized % 2 == 0 and bit == 1:
             quantized += 1 if coef >= quantized * quant_step else -1
         elif quantized % 2 == 1 and bit == 0:
@@ -358,13 +476,35 @@ def _embed_bit_in_coeff(coef: float, bit: int, quant_step: int = QUANT_STEP) ->
 
 
 def _extract_bit_from_coeff(coef: float, quant_step: int = QUANT_STEP) -> int:
+    """
+    Extract a bit from a DCT coefficient.
+
+    The inverse of _embed_bit_in_coeff. We round to the quantization grid
+    and check if it's odd (1) or even (0).
+
+    This is why QIM is robust: small noise in the coefficient usually
+    doesn't change which grid point we round to.
+    """
     quantized = round(coef / quant_step)
     return int(quantized % 2)
 
 
 def _generate_block_order(num_blocks: int, seed: bytes) -> list:
+    """
+    Generate a pseudo-random order for processing blocks.
+
+    This is crucial for security - if we just went left-to-right, top-to-bottom,
+    anyone could find the message by checking blocks in order. Instead, we
+    use a keyed shuffle so only someone with the same seed can find the data.
+
+    The seed comes from the crypto layer (derived from passphrase + photo + pin),
+    so the block order is effectively part of the encryption.
+    """
+    # Use SHA-256 to expand the seed into randomness
     hash_bytes = hashlib.sha256(seed).digest()
+    # Seed numpy's RNG (we use RandomState for reproducibility across versions)
     rng = np.random.RandomState(int.from_bytes(hash_bytes[:4], "big"))
+    # Fisher-Yates shuffle
     order = list(range(num_blocks))
     rng.shuffle(order)
     return order
@@ -393,14 +533,28 @@ def _save_color_image(rgb_array: np.ndarray, output_format: str = OUTPUT_FORMAT_
 
 
 def _rgb_to_ycbcr(rgb: np.ndarray) -> tuple[np.ndarray, np.ndarray, np.ndarray]:
+    """
+    Convert RGB to YCbCr color space.
+
+    YCbCr separates brightness (Y) from color (Cb=blue-ish, Cr=red-ish).
+    This is what JPEG uses internally, and it's great for us because:
+    - Human eyes are WAY more sensitive to brightness than color
+    - We can hide data in Y without it being as visible
+    - Cb/Cr are often subsampled (4:2:0) so Y has more capacity anyway
+
+    The coefficients here are from ITU-R BT.601 - the standard for video.
+    """
     R = rgb[:, :, 0].astype(np.float64)
     G = rgb[:, :, 1].astype(np.float64)
     B = rgb[:, :, 2].astype(np.float64)
 
+    # Y = luminance (brightness). Green contributes most because eyes are most sensitive to it.
     Y = np.array(0.299 * R + 0.587 * G + 0.114 * B, dtype=np.float64, copy=True, order="C")
+    # Cb = blue-difference chroma (centered at 128)
     Cb = np.array(
         128 - 0.168736 * R - 0.331264 * G + 0.5 * B, dtype=np.float64, copy=True, order="C"
     )
+    # Cr = red-difference chroma (centered at 128)
     Cr = np.array(
         128 + 0.5 * R - 0.418688 * G - 0.081312 * B, dtype=np.float64, copy=True, order="C"
     )
@@ -409,6 +563,12 @@ def _rgb_to_ycbcr(rgb: np.ndarray) -> tuple[np.ndarray, np.ndarray, np.ndarray]:
 
 
 def _ycbcr_to_rgb(Y: np.ndarray, Cb: np.ndarray, Cr: np.ndarray) -> np.ndarray:
+    """
+    Convert YCbCr back to RGB.
+
+    After embedding in the Y channel, we need to reconstruct RGB for display.
+    The Cb/Cr channels are unchanged - we only touched luminance.
+    """
     R = Y + 1.402 * (Cr - 128)
     G = Y - 0.344136 * (Cb - 128) - 0.714136 * (Cr - 128)
     B = Y + 1.772 * (Cb - 128)

src/stegasoo/steganography.py

@@ -1,21 +1,27 @@
 """
 Stegasoo Steganography Functions (v3.2.0)
 
-LSB and DCT embedding modes with pseudo-random pixel/coefficient selection.
+This is the core embedding/extraction module. Two modes available:
 
-Changes in v3.0:
+LSB (Least Significant Bit) Mode:
-- DCT domain embedding mode (requires scipy)
+- Classic steganography technique - hide bits in the least significant bit of pixel values
-- embed_mode parameter for encode/decode
+- Works on any image, outputs lossless PNG/BMP
-- Auto-detection of embedding mode
+- Higher capacity than DCT, but destroyed by JPEG compression
-- Comparison utilities
+- Great for: high-capacity needs, lossless workflows
 
-Changes in v3.0.1:
+DCT Mode (see dct_steganography.py):
-- dct_output_format parameter for DCT mode ('png' or 'jpeg')
+- Hides data in frequency-domain coefficients
-- dct_color_mode parameter for DCT mode ('grayscale' or 'color')
+- Survives some image processing, works with JPEG
+- Lower capacity but more robust
+- Great for: JPEG images, robustness needs
 
-Changes in v3.2.0:
+Both modes use pseudo-random pixel/coefficient selection based on a key.
-- Fixed HEADER_OVERHEAD constant (65 bytes, not 104 - date field removed)
+Without the key, you don't know where to look - security through obscurity
-- Updated ENCRYPTION_OVERHEAD calculation
+PLUS actual encryption of the payload.
+
+v3.0: Added DCT mode with scipy
+v3.0.1: DCT output format options (PNG/JPEG, grayscale/color)
+v3.2.0: Fixed overhead calculations after removing date field
 """
 
 import io
@@ -83,24 +89,31 @@ EXT_TO_FORMAT = {
 }
 
 # =============================================================================
-# OVERHEAD CONSTANTS (v4.0.0 - Updated for channel key support)
+# OVERHEAD CONSTANTS
 # =============================================================================
-# v4.0.0 Header format (with flags byte for channel key indicator):
-#   Magic:   4 bytes  (\x89ST3)
-#   Version: 1 byte   (5 for v4.0.0)
-#   Flags:   1 byte   (bit 0 = has channel key)
-#   Salt:    32 bytes
-#   IV:      12 bytes
-#   Tag:     16 bytes
-#   -----------------
-#   Total:   66 bytes
 #
-# v3.2.0 had 65 bytes (no flags byte)
+# Every stego image has some overhead before the actual payload:
-# v3.1.0 had date field (10 bytes + 1 byte length) = 76 bytes header
+#
+# The encrypted message format (v4.0.0):
+# ┌─────────────────────────────────────────────────────────────────┐
+# │ \x89ST3 │ v5 │ flags │  salt (32)  │  iv (12)  │  tag (16)  │ ... │
+# │ magic  │ ver│       │             │           │            │ data│
+# └─────────────────────────────────────────────────────────────────┘
+#   4 bytes  1    1         32            12           16         var
+#
+# Plus LSB embedding adds a 4-byte length prefix so we know where to stop.
+#
+# History of overhead sizes (in case you're debugging old images):
+# - v3.1.0: 76 bytes (had date field - 10+1 bytes)
+# - v3.2.0: 65 bytes (removed date, simpler)
+# - v4.0.0: 66 bytes (added flags byte for channel key)
 
-HEADER_OVERHEAD = 66  # v4.0.0: Magic + version + flags + salt + iv + tag
+HEADER_OVERHEAD = 66  # What the crypto layer adds to any message
-LENGTH_PREFIX = 4  # 4 bytes for payload length in LSB embedding
+LENGTH_PREFIX = 4     # We prepend the payload length for LSB extraction
-ENCRYPTION_OVERHEAD = HEADER_OVERHEAD + LENGTH_PREFIX  # 70 bytes total
+ENCRYPTION_OVERHEAD = HEADER_OVERHEAD + LENGTH_PREFIX  # Total: 70 bytes
+
+# That 70 bytes is your minimum image capacity requirement.
+# A tiny 100x100 image gives you ~3750 bytes capacity, minus 70 = ~3680 usable.
 
 # DCT output format options (v3.0.1)
 DCT_OUTPUT_PNG = "png"
@@ -456,6 +469,20 @@ def compare_modes(image_data: bytes) -> dict:
 # =============================================================================
 # PIXEL INDEX GENERATION
 # =============================================================================
+#
+# The key insight: we don't hide data in sequential pixels (that's easy to find).
+# Instead, we scatter the data across pseudo-random pixel locations.
+#
+# The pixel selection key (derived from passphrase + photo + pin) determines
+# WHICH pixels get modified. Without the key, an attacker would have to:
+# 1. Know we're using LSB steganography
+# 2. Try every possible subset of pixels
+# 3. Decrypt the result (which they also can't do without the key)
+#
+# We use ChaCha20 as a CSPRNG (Cryptographically Secure PRNG). It's:
+# - Fast (faster than AES-CTR on most CPUs)
+# - Deterministic (same key = same sequence, needed for extraction)
+# - Secure (can't predict the sequence without the key)
 
 
 @debug.time
@@ -463,8 +490,13 @@ def generate_pixel_indices(key: bytes, num_pixels: int, num_needed: int) -> list
     """
     Generate pseudo-random pixel indices for embedding.
 
-    Uses ChaCha20 as a CSPRNG seeded by the key to deterministically
+    This is the "where do we hide the bits?" function. We use ChaCha20
-    select which pixels will hold hidden data.
+    to generate a deterministic sequence of pixel indices that only
+    someone with the same key can reproduce.
+
+    Two strategies based on how much of the image we're using:
+    - >= 50% capacity: Full Fisher-Yates shuffle (sample without replacement)
+    - < 50% capacity: Direct random sampling (faster, same result)
     """
     debug.validate(len(key) == 32, f"Pixel key must be 32 bytes, got {len(key)}")
     debug.validate(num_pixels > 0, f"Number of pixels must be positive, got {num_pixels}")
@@ -475,6 +507,8 @@ def generate_pixel_indices(key: bytes, num_pixels: int, num_needed: int) -> list
 
     debug.print(f"Generating {num_needed} pixel indices from {num_pixels} total pixels")
 
+    # Strategy 1: Full shuffle when we need a lot of pixels
+    # Fisher-Yates shuffle is O(n) and gives us perfect random sampling
     if num_needed >= num_pixels // 2:
         debug.print(f"Using full shuffle (needed {num_needed}/{num_pixels} pixels)")
         nonce = b"\x00" * 16
@@ -482,8 +516,10 @@ def generate_pixel_indices(key: bytes, num_pixels: int, num_needed: int) -> list
         encryptor = cipher.encryptor()
 
         indices = list(range(num_pixels))
+        # Get enough random bytes to do the shuffle
         random_bytes = encryptor.update(b"\x00" * (num_pixels * 4))
 
+        # Fisher-Yates shuffle - swap each element with a random earlier element
         for i in range(num_pixels - 1, 0, -1):
             j_bytes = random_bytes[(num_pixels - 1 - i) * 4 : (num_pixels - i) * 4]
             j = int.from_bytes(j_bytes, "big") % (i + 1)
@@ -493,14 +529,17 @@ def generate_pixel_indices(key: bytes, num_pixels: int, num_needed: int) -> list
         debug.print(f"Generated {len(selected)} indices via shuffle")
         return selected
 
+    # Strategy 2: Direct sampling when we need fewer pixels
+    # Generate random indices until we have enough unique ones
     debug.print(f"Using optimized selection (needed {num_needed}/{num_pixels} pixels)")
     selected = []
-    used = set()
+    used = set()  # Track which pixels we've already picked
 
     nonce = b"\x00" * 16
     cipher = Cipher(algorithms.ChaCha20(key, nonce), mode=None, backend=default_backend())
     encryptor = cipher.encryptor()
 
+    # Pre-generate 2x the bytes we think we'll need (for collision handling)
     bytes_needed = (num_needed * 2) * 4
     random_bytes = encryptor.update(b"\x00" * bytes_needed)
 
@@ -514,8 +553,9 @@ def generate_pixel_indices(key: bytes, num_pixels: int, num_needed: int) -> list
             used.add(idx)
             selected.append(idx)
         else:
-            collisions += 1
+            collisions += 1  # Birthday paradox in action
 
+    # Edge case: ran out of pre-generated bytes (very high collision rate)
     if len(selected) < num_needed:
         debug.print(f"Need {num_needed - len(selected)} more indices, generating...")
         extra_needed = num_needed - len(selected)
@@ -539,6 +579,23 @@ def generate_pixel_indices(key: bytes, num_pixels: int, num_needed: int) -> list
 # =============================================================================
 # EMBEDDING FUNCTIONS
 # =============================================================================
+#
+# The actual bit-hiding magic happens here. LSB embedding is conceptually simple:
+#
+# Original pixel RGB: (142, 87, 201)
+# In binary:          (10001110, 01010111, 11001001)
+#                                      ^       ^       ^
+#                      These are the LSBs (least significant bits)
+#
+# To hide the bits [1, 0, 1]:
+# Modified pixel RGB: (10001111, 01010110, 11001001) = (143, 86, 201)
+#                                      ^       ^       ^
+#                      Changed!     Changed!  Already 1, no change needed
+#
+# The human eye can't see the difference between 142 and 143.
+# But we've hidden 3 bits of secret data in one pixel.
+#
+# With a 1000x1000 image: 1 million pixels * 3 channels = 3 million bits = 375 KB!
 
 
 @debug.time